Fault protection self-healing control method and system suitable for weak power grid

Abstract

The invention relates to the technical field of power distribution networks, in particular to a fault protection self-healing control method and system suitable for a weak power grid. The method comprises the following steps: presetting a voltage sensor, a current sensor and a power sensor, starting data acquisition, and acquiring monitoring data in real time; transmitting the monitoring data to a control center; presetting an initial value of a protection action threshold value of each position; updating the protection action threshold value of each position according to the judged fault type; the protection action duration of each position is adjusted according to the fluctuation degree of the system; and performing on-line continuous monitoring on the operation state of the power grid after power restoration. According to the scheme, the maximum fault current value and the protection action threshold value are calculated through theory and simulation analysis, recognition and isolation are carried out when faults occur, remote control is carried out according to system fluctuation, continuous monitoring is carried out after power supply is recovered, and system stability is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of power distribution network technology, and more specifically, to a fault protection self-healing control method and system applicable to weak power grids. Background Technology

[0002] In the field of power distribution networks, research on fault protection and self-healing control applicable to weak power grids typically employs advanced intelligent monitoring and analysis technologies. This involves real-time collection of power grid operation data, utilizing big data analytics and artificial intelligence algorithms to accurately locate fault points, and then achieving fault isolation and grid restoration through automated control methods such as rapid switching and load transfer. Its significance lies in its ability to greatly improve the power supply reliability of weak power grids, reduce outage time and scope, and ensure the stability of power supply for users. Its importance is self-evident; this is a key measure to improve the overall operational level of the power distribution network and meet the ever-increasing electricity demand.

[0003] Prior to this invention, existing fault protection self-healing control methods for weak power grids were mainly based on traditional relay protection principles. They handled faults by setting overcurrent and overvoltage protection settings, combined with reclosing and other methods. The technical challenge lies in the inherent fragility and limited power supply capacity of weak power grids, which are prone to complex problems such as voltage collapse and frequency instability during faults, and it is difficult to quickly and accurately determine the fault type and scope. The key is how to achieve effective fault detection and isolation under limited technical conditions, while simultaneously ensuring the stable operation of the power grid after a fault. Summary of the Invention

[0004] In view of the above problems, this invention proposes a fault protection self-healing control method and system suitable for weak power grids. It uses theoretical and simulation analysis to calculate the maximum fault current and protection action threshold, identifies and isolates faults, remotely controls based on system fluctuations, and continuously monitors after power supply is restored to ensure system stability.

[0005] According to a first aspect of the present invention, a fault protection self-healing control method suitable for weak power grids is provided.

[0006] In one or more embodiments, preferably, the fault protection self-healing control method for weak power grids includes:

[0007] Pre-set initial values ​​for protection action thresholds and protection action durations for each location in the power grid;

[0008] The voltage and current sensors deployed at various locations in the power grid are activated to collect real-time monitoring data of the power grid operation, including voltage and current signals.

[0009] The collected monitoring data is transmitted to the control center;

[0010] Fault type identification is performed based on the monitoring data;

[0011] The collected voltage and current signals are compared with the current protection action threshold. If the monitored signal exceeds the corresponding threshold and the duration reaches the current protection action duration, a protection output command is triggered to control the circuit breaker to isolate the fault area.

[0012] Update the protection action threshold for each location based on the determined fault type;

[0013] Adjust the protection action duration at each location according to the degree of system fluctuation;

[0014] After the fault isolation is completed, power supply to the non-faulty areas is restored, and the operation status of the restored power grid is monitored online based on continuously collected monitoring data.

[0015] Furthermore, the activation of voltage and current sensors deployed at various locations in the power grid to collect real-time monitoring data on power grid operation specifically includes:

[0016] Set the location of the voltage and current transformers;

[0017] Initiate real-time data acquisition;

[0018] The data acquired by the voltage and current transformers are transmitted to the acquisition unit according to a pre-set acquisition cycle.

[0019] Furthermore, the transmission of the monitoring data to the control center specifically includes:

[0020] After acquiring the monitoring data, the acquisition unit sends it to the merging unit;

[0021] The merging unit transmits the monitoring data to the control center according to the preset protocol.

[0022] Furthermore, the initial values ​​for setting protection action thresholds at various locations in the power grid specifically include:

[0023] The initial protection threshold coefficient for each location is set to 2;

[0024] The maximum value Z1 of the fault current in each branch is obtained by theoretical analysis;

[0025] The maximum value Z2 of the fault current for each DC circuit is obtained through simulation analysis.

[0026] Calculate the maximum fault value FM using the first calculation formula;

[0027] Based on the maximum fault value FM, the initial value C0 of the protection action threshold is calculated for each location using the second calculation formula;

[0028] The first calculation formula is:

[0029] FM = Max(Z1, Z2)

[0030] Where FM is the maximum fault value, Z1 is the theoretical maximum current, Z2 is the simulated maximum current, and Max() is the maximum value extraction function;

[0031] The second calculation formula is:

[0032] C0=B×FM

[0033] Where C0 is the initial value of the protection action threshold, and B is the protection threshold coefficient.

[0034] Furthermore, the update of the protection action threshold for each location based on the determined fault type specifically includes:

[0035] After a fault is detected, the fault type and location are identified online.

[0036] Determine the range of the fault's impact area at the current moment based on the fault type and location;

[0037] The initial value of the protection action threshold is updated at each location within the fault's influence range using a third calculation formula;

[0038] The third calculation formula is:

[0039] C0 = 1.3 × FM;

[0040] Where C0 is the initial value of the protection action threshold, and FM is the maximum fault value.

[0041] Furthermore, adjusting the protection action duration at each location based on the system's fluctuation level specifically includes:

[0042] The maximum voltage fluctuation at the current moment is obtained using the fourth calculation formula;

[0043] The maximum frequency fluctuation at the current moment can be obtained using the fifth calculation formula;

[0044] The fluctuation dimension is calculated using the sixth calculation formula based on the maximum voltage fluctuation and the maximum frequency fluctuation at the current moment.

[0045] Based on the fluctuation dimension, the protection action duration is updated using the seventh calculation formula;

[0046] The fourth calculation formula is:

[0047] UM = Maxf(△U)

[0048] Where Maxf() is the function to extract the maximum fluctuation within the preset analysis range f, UM is the maximum voltage fluctuation at the current moment, and ΔU is the absolute value of the voltage fluctuation at each location.

[0049] The fifth calculation formula is:

[0050] FM = Maxf(△F)

[0051] Where FM is the maximum frequency fluctuation at the current moment, and ΔF is the absolute value of the frequency fluctuation at each location;

[0052] The sixth calculation formula is:

[0053] BD is the fluctuation dimension = K1×FM + K2×UM

[0054] Wherein, K1 is the preset first conversion coefficient, and K2 is the preset second conversion coefficient;

[0055] The seventh calculation formula is:

[0056] TB=30ms, BD>1

[0057] TB=80ms, 0.5≤BD≤1

[0058] TB=150ms, BD<0.5

[0059] TB represents the duration of the protection action.

[0060] Furthermore, after completing fault isolation, restoring power supply to the non-faulty areas and monitoring the restored grid operation status online based on continuously collected monitoring data specifically includes:

[0061] After the protection action, power supply to the non-faulty area is restored;

[0062] After power is restored, continue to monitor the power grid's operational status;

[0063] When the operating status changes again and an anomaly occurs, the fault protection self-healing control is restarted.

[0064] According to a second aspect of the present invention, a fault protection self-healing control system suitable for weak power grids is provided.

[0065] In one or more embodiments, preferably, the fault protection self-healing control system suitable for weak power grids includes:

[0066] The initial value setting module is used to pre-set the initial values ​​of the protection action threshold and the initial values ​​of the protection action duration for each location in the power grid;

[0067] The real-time data acquisition module is used to activate voltage and current sensors deployed at various locations in the power grid to collect real-time monitoring data of the power grid operation, including voltage signals and current signals.

[0068] The data fast transmission module is used to transmit the collected monitoring data to the control center;

[0069] The fault identification module is used to identify the fault type based on the monitoring data;

[0070] The fault isolation module is used to compare the collected voltage and current signals with the current protection action threshold. If the monitored signal exceeds the corresponding threshold and the duration reaches the current protection action duration, a protection output command is triggered to control the circuit breaker to isolate the fault area.

[0071] The protection action threshold update module is used to update the protection action threshold for each location based on the determined fault type.

[0072] The protection action duration update module is used to adjust the protection action duration at each location according to the degree of system fluctuation.

[0073] The continuous monitoring module is used to restore power supply to non-faulty areas after fault isolation is completed, and to monitor the power grid operation status online based on continuously collected monitoring data.

[0074] According to a third aspect of the present invention, a computer-readable storage medium is provided that stores computer program instructions thereon, which, when executed by a processor, implement the method as described in any one of the first aspects of the present invention.

[0075] According to a fourth aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the memory is used to store one or more computer program instructions, wherein the one or more computer program instructions are executed by the processor to implement the method described in any one aspect of the present invention.

[0076] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0077] In this invention, an algorithm is used to identify the fault type and location, and then update the protection action threshold. The advantages are improved fault isolation accuracy, rapid fault location, reduced fault impact, and ensured stable operation of the power system.

[0078] In this invention, voltage and frequency fluctuations are calculated, and the protection action duration is adjusted accordingly. The advantage is that it allows for flexible control based on system fluctuations, enhancing the system's ability to cope with different operating conditions and improving power supply reliability.

[0079] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0080] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0081] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0082] Figure 1 This is a flowchart of a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0083] Figure 2 This is a flowchart illustrating the process of pre-setting voltage, current, and power sensors, initiating data acquisition, and obtaining real-time monitoring data in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0084] Figure 3 This is a flowchart illustrating the transmission of monitoring data to the control center in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0085] Figure 4 This is a flowchart illustrating the initial value of the protection action threshold for each location in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0086] Figure 5 This is a flowchart illustrating the updating of the protection action threshold for each location based on the determined fault type in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0087] Figure 6 This is a flowchart illustrating the adjustment of the protection action duration at each location based on the degree of system fluctuation in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0088] Figure 7 This is a flowchart illustrating the online and continuous monitoring of the power grid operation status after power restoration in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0089] Figure 8 This is a structural diagram of a fault protection self-healing control system for weak power grids according to an embodiment of the present invention.

[0090] Figure 9 This is a structural diagram of an electronic device according to one embodiment of the present invention. Detailed Implementation

[0091] In some of the processes described in the specification, claims, and accompanying drawings of this invention, multiple operations appearing in a specific order are included. However, it should be clearly understood that these operations may not be executed in the order they appear herein, or may be executed in parallel. The operation numbers, such as 101, 102, etc., are merely used to distinguish different operations and do not represent any execution order. Furthermore, these processes may include more or fewer operations, and these operations may be executed sequentially or in parallel. It should be noted that the descriptions such as "first," "second," etc., in this document are used to distinguish different messages, devices, modules, etc., and do not represent a sequential order, nor do they limit "first" and "second" to different types.

[0092] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0093] In the field of power distribution networks, research on fault protection and self-healing control applicable to weak power grids typically employs advanced intelligent monitoring and analysis technologies. This involves real-time collection of power grid operation data, utilizing big data analytics and artificial intelligence algorithms to accurately locate fault points, and then achieving fault isolation and grid restoration through automated control methods such as rapid switching and load transfer. Its significance lies in its ability to greatly improve the power supply reliability of weak power grids, reduce outage time and scope, and ensure the stability of power supply for users. Its importance is self-evident; this is a key measure to improve the overall operational level of the power distribution network and meet the ever-increasing electricity demand.

[0094] Prior to this invention, existing fault protection self-healing control methods for weak power grids were mainly based on traditional relay protection principles. They handled faults by setting overcurrent and overvoltage protection settings, combined with reclosing and other methods. The technical challenge lies in the inherent fragility and limited power supply capacity of weak power grids, which are prone to complex problems such as voltage collapse and frequency instability during faults, and it is difficult to quickly and accurately determine the fault type and scope. The key is how to achieve effective fault detection and isolation under limited technical conditions, while simultaneously ensuring the stable operation of the power grid after a fault.

[0095] This invention provides a fault protection self-healing control method and system suitable for weak power grids. This scheme utilizes theoretical and simulation analysis to calculate the maximum fault current and protection action threshold, identifies and isolates faults during operation, remotely controls based on system fluctuations, and continuously monitors the system after power restoration to ensure system stability.

[0096] According to a first aspect of the present invention, a fault protection self-healing control method suitable for weak power grids is provided.

[0097] Figure 1 This is a flowchart of a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0098] In one or more embodiments, preferably, the fault protection self-healing control method for weak power grids includes:

[0099] S101. Pre-set the voltage, current and power sensors, start data acquisition, and obtain monitoring data in real time;

[0100] S102. Transmit the monitoring data to the control center;

[0101] S103. Preset the initial value of the protection action threshold for each position;

[0102] S104. Update the protection action threshold for each location based on the determined fault type;

[0103] S105. Adjust the protection action duration at each location according to the degree of system fluctuation;

[0104] S106. Conduct online and continuous monitoring of the power grid operation status after power supply is restored.

[0105] In this embodiment of the invention, voltage, current, and power sensors and transformers are installed at key nodes to collect data in real time and transmit it to the acquisition unit periodically. The acquisition unit transmits the data to the merging unit, which then sends it to the control center via the network after protocol conversion. The maximum value of the fault current is determined through theoretical and simulation analysis, and the initial value of the protection action threshold is calculated. During a fault, fault waveform recording and diagnostic algorithms are used to identify the fault type and location, and the threshold is updated for isolation. The fluctuation dimension is calculated based on voltage and frequency fluctuations, and the protection action duration is adjusted accordingly. After power is restored from the fault, the grid operation is continuously monitored, and the fault protection self-healing control is restarted when an anomaly occurs.

[0106] Figure 2 This is a flowchart illustrating the process of pre-setting voltage, current, and power sensors, initiating data acquisition, and obtaining real-time monitoring data in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0107] like Figure 2As shown, in one or more embodiments, preferably, the sensor with pre-set voltage, current, and power, upon initiating data acquisition and obtaining monitoring data in real time, specifically includes:

[0108] S201. Set the position of the voltage and current transformers;

[0109] S202, Start real-time data acquisition;

[0110] S203. The acquired data is transmitted to the acquisition unit according to the preset acquisition cycle.

[0111] In this embodiment of the invention, firstly, key nodes requiring monitoring are identified in the power system, such as the incoming and outgoing lines of substations and connection points of important electrical equipment, and voltage, current, and power sensors are installed. For example, in the power supply system of a factory, sensors are installed at the incoming lines of its main distribution room and at the front ends of electrical equipment on important production lines. These sensors are devices capable of accurately measuring and outputting corresponding physical quantity signals. Next, the locations of voltage and current transformers are determined, and the transformers are installed between the sensors and the monitoring lines. The transformers are used to proportionally transform voltage or current so that the sensors can accurately measure larger voltage and current values. After installation, a real-time data acquisition program is started, enabling the sensors to acquire monitoring data in real time. The acquired data is transmitted to the acquisition unit via wired or wireless transmission according to a pre-set acquisition cycle, such as every 100 milliseconds. This acquisition unit is a device with data receiving and preliminary processing functions, thereby realizing the acquisition of real-time data from the power system. The sensor installation details are as follows: when installing sensors at the identified key node locations, a suitable installation method must be selected based on the electrical characteristics of the nodes. For example, for substation incoming and outgoing lines, due to their high voltage levels, through-wall or pillar-mounted installation methods can be used to ensure reliable electrical connection and good insulation performance between the sensor and the line. For connection points of important electrical equipment, if space is limited, miniaturized, modular sensors can be selected and installed on rails in distribution cabinets near the equipment. The selection and installation process of instrument transformers includes: when setting the positions of voltage and current transformers, the appropriate transformer ratio must be selected based on the voltage and current levels of the monitored line and the input range of the sensor. For example, for a 10kV line, a 10kV / 100V voltage transformer and a 100A / 5A current transformer can be selected. During installation, ensure that the primary side of the transformer is connected in series (current transformer) or parallel (voltage transformer) with the monitored line, and that the secondary side is correctly connected to the corresponding input port of the sensor. Also, ensure that the polarity of the transformer is not reversed. The data transmission method is selected based on the following: the collected data is transmitted to the acquisition unit according to a pre-set acquisition cycle (e.g., every 100 milliseconds). The choice of transmission method depends on the site environment and data transmission requirements. In scenarios with low interference and short distances, such as when the distance from the factory's internal power distribution room to the acquisition unit is within 100 meters, wired transmission using an RS-485 bus can be used, which has the advantages of low cost and strong anti-interference capability. If the distance is long and there is a lot of electromagnetic interference on site, or wiring is difficult, a wireless transmission method, such as LoRa wireless communication technology, can be selected. Its transmission distance can reach several kilometers and it can adapt to complex industrial environments.

[0112] Figure 3 This is a flowchart illustrating the transmission of monitoring data to the control center in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0113] like Figure 3 As shown, in one or more embodiments, preferably, the step of transmitting the monitoring data to the control center specifically includes:

[0114] S301. After acquiring the monitoring data, the acquisition unit sends it to the merging unit;

[0115] S302. The merging unit transmits data to the control center according to the preset protocol.

[0116] In this embodiment, after the acquisition unit obtains real-time monitoring data, such as voltage, current, and power data received from sensors at the front end of the factory's power distribution room and production line equipment, it immediately sends this data to the merging unit. The merging unit is a device with data integration and protocol conversion functions. It organizes and packages the received data according to a preset specific data transmission protocol, such as the Modbus protocol, converting it into a format suitable for network transmission. Then, it transmits the data to the control center via a high-speed network, such as Ethernet. The control center is the core location for centralized management and control of the entire power system, thus enabling rapid transmission of monitoring data to the control center. First, the hardware architecture of the merging unit is as follows: The merging unit is a device with data integration and protocol conversion functions. Its hardware typically includes a central processing unit (CPU), a data storage module, and a communication interface module. The CPU is responsible for data processing and protocol conversion calculations. The data storage module is used to temporarily store the received data. The communication interface module includes various interface types, such as an Ethernet interface for communication with the control center and an RS-485 interface for communication with the acquisition unit, ensuring smooth data interaction between different devices. The data processing and packaging process includes: When the merging unit processes and packages the received data according to the preset Modbus protocol, it first classifies and arranges the raw data sent by the acquisition unit according to the frame format requirements of the Modbus protocol. For example, different types of data such as voltage, current, and power are organized according to the address and data type specified in the protocol, and information such as frame headers, frame trailers, and checksums are added to form complete Modbus data frames for reliable transmission in the network.

[0117] Figure 4 This is a flowchart illustrating the initial value of the protection action threshold for each location in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0118] like Figure 4 As shown, in one or more embodiments, preferably, the initial value of the pre-set protection action threshold for each location specifically includes:

[0119] S401. Set the initial protection threshold coefficient to 2 for each location;

[0120] S402. Use theoretical analysis to obtain the maximum value of the fault current for each branch;

[0121] S403. Use simulation analysis to obtain the maximum value of the fault current for each DC current.

[0122] S404. Calculate the maximum fault value using the first calculation formula;

[0123] S405. Calculate the initial value of the protection action threshold for each position using the second calculation formula;

[0124] The first calculation formula is:

[0125] FM = Max(Z1, Z2)

[0126] Where FM is the maximum fault value, Z1 is the theoretical maximum current, Z2 is the simulated maximum current, and Max() is the maximum value extraction function;

[0127] The second calculation formula is:

[0128] C0=B×FM

[0129] Where C0 is the initial value of the protection action threshold, and B is the protection threshold coefficient.

[0130] In this embodiment, for each monitoring location in the power system, an initial protection threshold coefficient of 2 is first set. This coefficient is an important parameter used for subsequent calculation of the protection action threshold. Then, using theoretical analysis methods, based on information such as the power system topology, component parameters, and operating mode, the maximum value of the fault current in each branch is calculated. For example, in a simple ring power grid, the maximum value of the fault current in each branch is calculated using theoretical formulas such as Kirchhoff's laws. Simultaneously, using simulation analysis software, such as PSCAD software, a power system model is built to simulate various fault conditions, thereby obtaining the maximum value of the fault current in each DC circuit. Next, the maximum fault value is calculated using the first calculation formula FM = Max(Z1, Z2), where Z1 is the theoretical maximum current, Z2 is the simulated maximum current, and Max() is the maximum value extraction function, i.e., selecting the larger value between Z1 and Z2 as FM. Finally, for each location, the initial value of the protection action threshold is calculated using the second calculation formula C0 = B × FM, where C0 is the initial value of the protection action threshold, and B is the previously set protection threshold coefficient of 2, thus determining the initial value of the protection action threshold for each location. The specific steps of the theoretical analysis are as follows: When calculating the maximum fault current of each branch using theoretical analysis methods, taking a simple ring network as an example, firstly, the node current equations and loop voltage equations of the network are listed according to Kirchhoff's Current Law (KCL) and Voltage Law (KVL). Then, the parameters of each component in the network, such as resistance, inductance, and capacitance, as well as the operating parameters of the power supply, such as voltage and frequency, are substituted into the equations. By solving these equations, the current expressions of each branch under different fault conditions are obtained, and then the maximum fault current of each branch is calculated. The simulation analysis software operation process includes: When building a power system model using PSCAD software, firstly, select the corresponding electrical component library in the software interface, such as the power supply component library, transmission line component library, load component library, etc., and drag and drop these components into the working area and connect them according to the topology of the actual power system. Set the parameters of each component to be consistent with the actual system. Then, set various fault types and fault times in the software, such as setting parameters such as short-circuit resistance, short-circuit location, and short-circuit occurrence time for short-circuit faults. When the simulation program is run, the software will perform calculations based on the set model and parameters, and output the curves of the fault current of each DC over time, from which the maximum value of the fault current can be obtained.

[0131] Figure 5 This is a flowchart illustrating the updating of the protection action threshold for each location based on the determined fault type in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0132] like Figure 5As shown, in one or more embodiments, preferably, updating the protection action threshold for each location based on the determined fault type specifically includes:

[0133] S501. After a fault is detected, the fault type and fault location are identified online.

[0134] S502. Determine the range of the fault's impact location at the current moment based on the fault type and fault location;

[0135] S503. Update the initial value of the protection action threshold at each location within the fault influence range using the third calculation formula;

[0136] The third calculation formula is:

[0137] C0 = 1.3 × FM.

[0138] In this embodiment, when the power system detects a fault, it immediately initiates an online fault type and location identification procedure. For example, it uses fault transient electrical quantity characteristics recorded by a fault recording device and a fault diagnosis algorithm to determine the fault type (e.g., short circuit, open circuit) and fault location. Based on the determined fault type and location, combined with the power system's topology and operating mode, the current fault impact range is determined. For instance, in a radial distribution network, if a short circuit fault occurs on a branch line, the impact range is that branch line and all downstream nodes. Then, at each location within the fault impact range, the initial value of the protection action threshold is updated using the third calculation formula C0 = 1.3 × FM, where FM is the previously calculated maximum fault value. This method updates the protection action threshold for more accurate fault isolation operations later. The fault diagnosis algorithm works by using fault transient electrical quantity characteristics recorded by a fault recording device to determine the fault type and fault location. Taking a fault diagnosis algorithm based on wavelet transform as an example, the transient electrical signals such as voltage and current recorded by the fault recording device are first subjected to wavelet transform, decomposing the signals into components of different frequencies. The transient signals corresponding to different fault types and fault locations exhibit different characteristics after wavelet transform; for example, short-circuit faults show significant changes in high-frequency components. By analyzing these characteristics and comparing them with a pre-established fault feature database, the fault type and location can be determined. The specific method for determining the fault's influence range is as follows: In a radial distribution network, if a short-circuit fault occurs on a branch line, to determine the fault's influence range, first, based on the distribution network's topology information, a search is performed from the fault location downstream of the line. Using a breadth-first search algorithm or a depth-first search algorithm, the nodes and lines in the distribution network are traversed, and all nodes and lines connected to the faulty branch line and located downstream of it are determined as the fault's influence range, i.e., the branch line and all its downstream nodes.

[0139] Figure 6 This is a flowchart illustrating the adjustment of the protection action duration at each location based on the degree of system fluctuation in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0140] like Figure 6 As shown, in one or more embodiments, preferably, adjusting the protection action duration at each location according to the system fluctuation level specifically includes:

[0141] S601. Use the fourth calculation formula to obtain the maximum voltage fluctuation at the current moment;

[0142] S602. Use the fifth calculation formula to obtain the maximum frequency fluctuation at the current moment;

[0143] S603. Calculate the fluctuation dimension using the sixth calculation formula;

[0144] S604. Update the protection action duration using the seventh calculation formula;

[0145] The fourth calculation formula is:

[0146] UM = Maxf(△U)

[0147] Where Maxf() is the function to extract the maximum fluctuation within the preset analysis range f, UM is the maximum voltage fluctuation at the current moment, and ΔU is the absolute value of the voltage fluctuation at each location.

[0148] The fifth calculation formula is:

[0149] FM = Maxf(△F)

[0150] Where FM is the maximum frequency fluctuation at the current moment, and ΔF is the absolute value of the frequency fluctuation at each location;

[0151] The sixth calculation formula is:

[0152] BD is the fluctuation dimension = K1×FM + K2×UM

[0153] Wherein, K1 is the preset first conversion coefficient, and K2 is the preset second conversion coefficient;

[0154] The seventh calculation formula is:

[0155] TB=30ms, BD>1

[0156] TB=80ms, 0.5≤BD≤1

[0157] TB=150ms, BD<0.5

[0158] TB represents the duration of the protection action.

[0159] In this embodiment, the maximum voltage fluctuation at the current moment is first obtained using the fourth calculation formula UM = Maxf(△U), where Maxf() is a function to extract the maximum fluctuation within a preset analysis range f, and △U is the absolute value of the voltage fluctuation at each location. For example, if the analysis range f is set to the past 10 seconds, the absolute value of the voltage fluctuation at each location in the power system is calculated, and the maximum value is taken as UM. Next, the maximum frequency fluctuation at the current moment is obtained using the fifth calculation formula FM = Maxf(△F), where △F is the absolute value of the frequency fluctuation at each location. Similarly, the absolute value of the frequency fluctuation at each location is calculated within the preset analysis range, and the maximum value is taken as FM. Then, the fluctuation dimension is calculated using the sixth calculation formula BD = fluctuation dimension = K1×FM + K2×UM, where K1 is a preset first conversion coefficient, and K2 is a preset second conversion coefficient, for example, K1 = 0.5, K2 = 0.5. Finally, the protection action duration TB is updated based on the fluctuation dimension BD using the seventh calculation formula. When BD > 1, TB = 30ms; when 0.5 ≤ BD ≤ 1, TB = 80ms; when BD < 0.5, TB = 150ms. This adjusts the protection action duration at each location according to the system's fluctuation level. Specifically, the calculation of voltage and frequency fluctuations is implemented as follows: When using the fourth calculation formula UM = Maxf(△U) to obtain the maximum voltage fluctuation at the current moment, taking the analysis range f as the past 10 seconds as an example, voltage data is first collected in real time by voltage monitoring devices installed at various locations in the power system, such as smart meters or phasor measurement units. Voltage values ​​are recorded at regular time intervals (e.g., 10 milliseconds), and the absolute value of the voltage difference between two adjacent records is calculated as the voltage fluctuation △U within that time period. All calculated △U values ​​from the past 10 seconds are stored in an array, and then the Maxf() function is called. This function iterates through the array and finds the maximum value as the maximum voltage fluctuation UM at the current moment. The process of calculating frequency fluctuations is similar. Frequency data is collected through frequency monitoring equipment, the absolute value of frequency fluctuation ΔF is calculated, and then the maximum frequency fluctuation FM is obtained. The method for determining the conversion coefficients is as follows: the determination of the preset first conversion coefficient K1 and second conversion coefficient K2 requires extensive experiments and data analysis. First, under different power system operating conditions, data on system voltage fluctuations, frequency fluctuations, and corresponding protection action effects are collected. Then, data analysis methods, such as least squares or genetic algorithms, are used to process and optimize these data to find the optimal K1 and K2 values ​​for protection action effectiveness. For example, through multiple experiments and optimizations, it was determined that when K1 = 0.5 and K2 = 0.5, the adjustment of the protection action duration can better adapt to the operating needs of the power system under different fluctuation conditions.

[0160] Figure 7 This is a flowchart illustrating the online and continuous monitoring of the power grid operation status after power restoration in a fault protection self-healing control method applicable to weak power grids according to an embodiment of the present invention.

[0161] like Figure 7 As shown, in one or more embodiments, preferably, the online continuous monitoring of the power grid operation status after power restoration specifically includes:

[0162] S701. Power is restored after the protection action.

[0163] S702. After power supply is restored, continue to monitor the power grid's operating status;

[0164] S703. When the operating status changes again and an abnormality occurs, the fault protection self-healing control is restarted.

[0165] When a power system fault occurs and protection actions are executed, a series of recovery operations, such as disconnecting the faulty line and then reconnecting the backup line switch, restore power supply to the grid. After power supply is restored, monitoring equipment installed at various key locations in the grid, such as smart meters and phasor measurement units, continuously monitor the grid's operating status and collect real-time operating parameters such as voltage, current, and power. When these operating parameters show abnormal changes, such as voltage exceeding the normal allowable range or sudden current changes, the fault protection self-healing control program is immediately triggered to re-identify the fault type and location and perform subsequent fault isolation operations to ensure the safe and stable operation of the grid. The specific recovery operation process is as follows: When a power system fault occurs and protection actions are executed, power supply is restored. Taking disconnecting the faulty line and then reconnecting the backup line switch as an example, the protection device first detects the fault and sends a trip signal, tripping the circuit breaker of the faulty line. Then, the monitoring system receives the fault information and the trip signal, and determines the nature and scope of the fault. If a backup line exists, the monitoring system sends a closing command to the circuit breaker of the backup line. Before closing, the backup line needs to be checked, such as its insulation condition and the presence of any live foreign objects. After confirmation, the backup line switch is closed, restoring power to the grid. The selection and configuration of monitoring equipment includes: after power is restored, continuously monitoring the grid's operating status using monitoring equipment installed at various key locations on the grid. For smart meters, appropriate specifications can be selected based on the voltage level and load size of the monitoring location. For example, for a 10kV line, a smart meter with 10kV voltage measurement function and a corresponding current measurement range can be selected. When configuring smart meters, their communication parameters are set to enable data transmission with the upper-level monitoring system. For phasor measurement units (PMUs), appropriate accuracy and sampling frequency are selected based on the grid's synchronous phasor measurement requirements, such as an accuracy of 0.1% and a sampling frequency of 100Hz. These PMUs are installed at key nodes in the grid, such as the busbars of substations, to ensure accurate acquisition of voltage and current phasor information from the grid.

[0166] According to a second aspect of the present invention, a fault protection self-healing control system suitable for weak power grids is provided.

[0167] Figure 8 This is a structural diagram of a fault protection self-healing control system for weak power grids according to an embodiment of the present invention.

[0168] In one or more embodiments, preferably, the fault protection self-healing control system suitable for weak power grids includes:

[0169] The real-time data acquisition module 801 is used to pre-set the sensors for voltage, current and power, start data acquisition, and acquire monitoring data in real time;

[0170] Data transmission module 802 is used to transmit the monitoring data to the control center;

[0171] The fault identification module 803 is used to preset the initial value of the protection action threshold for each location;

[0172] The fault isolation module 804 is used to update the protection action threshold for each location based on the determined fault type.

[0173] The remote control module 805 is used to adjust the protection action duration at each location according to the fluctuation level of the system.

[0174] The continuous monitoring module 806 is used to continuously monitor the power grid operation status online after power is restored.

[0175] In this embodiment of the invention, a system suitable for different structures is realized through a series of modular designs. This system can achieve closed-loop, reliable, and efficient execution through data acquisition, analysis, and control.

[0176] According to a third aspect of the present invention, a computer-readable storage medium is provided that stores computer program instructions thereon, which, when executed by a processor, implement the method as described in any one of the first aspects of the present invention.

[0177] According to a fourth aspect of the present invention, an electronic device is provided. Figure 9 This is a structural diagram of an electronic device according to one embodiment of the present invention. Figure 9 The illustrated electronic device is a fault protection self-healing control device suitable for weak power grids. It includes a general computer hardware architecture, comprising at least a processor 901 and a memory 902. The processor 901 and memory 902 are connected via a bus 903. The memory 902 is adapted to store instructions or programs executable by the processor 901. The processor 901 can be a standalone microprocessor or a collection of one or more microprocessors. Thus, the processor 901 executes the instructions stored in the memory 902, thereby performing the method flow of the embodiments of the present invention as described above to process data and control other devices. The bus 903 connects the aforementioned components together, and also connects these components to a display controller 904, a display device, and an input / output (I / O) device 905. The input / output (I / O) device 905 can be a mouse, keyboard, modem, network interface, touch input device, motion-sensing input device, printer, and other devices known in the art. Typically, the input / output device 905 is connected to the system via an input / output (I / O) controller 906.

[0178] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0179] In this invention, an algorithm is used to identify the fault type and location, and then update the protection action threshold. The advantages are improved fault isolation accuracy, rapid fault location, reduced fault impact, and ensured stable operation of the power system.

[0180] In this invention, voltage and frequency fluctuations are calculated, and the protection action duration is adjusted accordingly. The advantage is that it allows for flexible control based on system fluctuations, enhancing the system's ability to cope with different operating conditions and improving power supply reliability.

[0181] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0182] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0183] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0184] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0185] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A fault protection self-healing control method applicable to weak power grids, characterized in that, include: Pre-set initial values ​​for protection action thresholds and protection action durations for each location in the power grid; The voltage and current sensors deployed at various locations in the power grid are activated to collect real-time monitoring data of the power grid operation, including voltage and current signals. The collected monitoring data is transmitted to the control center; Fault type identification is performed based on the monitoring data; The collected voltage and current signals are compared with the current protection action threshold. If the monitored signal exceeds the corresponding threshold and the duration reaches the current protection action duration, a protection output command is triggered to control the circuit breaker to isolate the fault area. Update the protection action threshold for each location based on the determined fault type; Adjust the protection action duration at each location according to the degree of system fluctuation; After the fault isolation is completed, power supply to the non-faulty areas is restored, and the operation status of the restored power grid is monitored online based on continuously collected monitoring data.

2. The fault protection self-healing control method for weak power grids as described in claim 1, characterized in that, The activation of voltage and current sensors deployed at various locations in the power grid to collect real-time monitoring data on power grid operation specifically includes: Set the location of the voltage and current transformers; Initiate real-time data acquisition; The data acquired by the voltage and current transformers are transmitted to the acquisition unit according to a pre-set acquisition cycle.

3. The fault protection self-healing control method for weak power grids as described in claim 2, characterized in that, The process of transmitting the monitoring data to the control center specifically includes: After acquiring the monitoring data, the acquisition unit sends it to the merging unit; The merging unit transmits the monitoring data to the control center according to the preset protocol.

4. The fault protection self-healing control method for weak power grids as described in claim 1, characterized in that, The initial values ​​for setting protection action thresholds at various locations in the power grid include: The initial protection threshold coefficient for each location is set to 2; The maximum value Z1 of the fault current in each branch is obtained by theoretical analysis; The maximum value Z2 of the fault current for each DC circuit is obtained through simulation analysis. Calculate the maximum fault value FM using the first calculation formula; Based on the maximum fault value FM, the initial value C0 of the protection action threshold is calculated for each location using the second calculation formula; The first calculation formula is: FM = Max(Z1, Z2); Where FM is the maximum fault value, Z1 is the theoretical maximum current, Z2 is the simulated maximum current, and Max() is the maximum value extraction function; The second calculation formula is: C0 = B × FM; Where C0 is the initial value of the protection action threshold, and B is the protection threshold coefficient.

5. The fault protection self-healing control method for weak power grids as described in claim 1, characterized in that, The step of updating the protection action threshold for each location based on the determined fault type specifically includes: After a fault is detected, the fault type and location are identified online. Determine the range of the fault's impact area at the current moment based on the fault type and location; The initial value of the protection action threshold is updated at each location within the fault's influence range using a third calculation formula; The third calculation formula is: C0 = 1.3 × FM; Where C0 is the initial value of the protection action threshold, and FM is the maximum fault value.

6. The fault protection self-healing control method for weak power grids as described in claim 1, characterized in that, The adjustment of the protection action duration at each location based on the system's fluctuation level specifically includes: The maximum voltage fluctuation at the current moment is obtained using the fourth calculation formula; The maximum frequency fluctuation at the current moment can be obtained using the fifth calculation formula; The fluctuation dimension is calculated using the sixth calculation formula based on the maximum voltage fluctuation and the maximum frequency fluctuation at the current moment. Based on the fluctuation dimension, the protection action duration is updated using the seventh calculation formula; The fourth calculation formula is: UM = Maxf(△U); Where Maxf() is the function to extract the maximum fluctuation within the preset analysis range f, UM is the maximum voltage fluctuation at the current moment, and ΔU is the absolute value of the voltage fluctuation at each location. The fifth calculation formula is: FM = Maxf(△F); Where FM is the maximum frequency fluctuation at the current moment, and ΔF is the absolute value of the frequency fluctuation at each location; The sixth calculation formula is: BD is the fluctuation dimension = K1×FM + K2×UM; Wherein, K1 is the preset first conversion coefficient, and K2 is the preset second conversion coefficient; The seventh calculation formula is: TB=30ms, BD>1; TB = 80ms, 0.5 ≤ BD ≤ 1; TB=150ms, BD<0.5; TB represents the duration of the protection action.

7. The fault protection self-healing control method for weak power grids as described in claim 1, characterized in that, After completing fault isolation, power supply is restored to the non-faulty areas, and the online monitoring of the restored power grid operation status is conducted based on continuously collected monitoring data. Specifically, this includes: After the protection action, power supply to the non-faulty area is restored; After power is restored, continue to monitor the power grid's operational status; When the operating status changes again and an anomaly occurs, the fault protection self-healing control is restarted.

8. A fault protection self-healing control system suitable for weak power grids, characterized in that, The system is used to implement the method as described in any one of claims 1-7, the system comprising: The initial value setting module is used to pre-set the initial values ​​of the protection action threshold and the initial values ​​of the protection action duration for each location in the power grid; The real-time data acquisition module is used to activate voltage and current sensors deployed at various locations in the power grid to collect real-time monitoring data of the power grid operation, including voltage signals and current signals. The data fast transmission module is used to transmit the collected monitoring data to the control center; The fault identification module is used to identify the fault type based on the monitoring data; The fault isolation module is used to compare the collected voltage and current signals with the current protection action threshold. If the monitored signal exceeds the corresponding threshold and the duration reaches the current protection action duration, a protection output command is triggered to control the circuit breaker to isolate the fault area. The protection action threshold update module is used to update the protection action threshold for each location based on the determined fault type. The protection action duration update module is used to adjust the protection action duration at each location according to the degree of system fluctuation. The continuous monitoring module is used to restore power supply to non-faulty areas after fault isolation is completed, and to monitor the power grid operation status online based on continuously collected monitoring data.

9. A computer-readable storage medium storing computer program instructions thereon, characterized in that, The computer program instructions, when executed by a processor, implement the method as described in any one of claims 1-7.

10. An electronic device comprising a memory and a processor, characterized in that, The memory is used to store one or more computer program instructions, wherein the one or more computer program instructions are executed by the processor to implement the method as described in any one of claims 1-7.

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