A method and system for coordinating control of internal and external power grids

Abstract

The application discloses a kind of inside and outside power grid machine grid coordination control method and system, it is related to electric power system automatic control technical field, comprising: based on enterprise internal power grid operation data and unified clock signal generation with time tag operation data;According to isolated network candidate trigger signal determines event reference time, filters the same event operation data group;Based on different types of operation data mutual authentication judges whether external power grid is really split;After confirming split, control turbine digital electro-hydraulic control system switches to speed control mode, and according to the load combination of pre-fault off-network power and priority selection to be cut;Through circuit breaker feedback and load electrical state confirmation actual cut power, and combined with the dynamic execution of supplementary load shedding of unit speed or power grid frequency variation, realize isolated network stability control, solve the problems that the existing machine grid coordination control method has insufficient time sequence correlation ability when multiple source operation data, low accuracy of isolated network judgment, and the actual cut state of load is difficult to accurately confirm.

Description

Technical Field

[0001] This invention relates to the field of power system automatic control technology, specifically to a method and system for coordinated control of internal and external power grids. Background Technology

[0002] With the development of self-provided power generation systems in large industrial enterprises such as coking, metallurgy, and chemical industries, the internal power grid of these enterprises is usually powered by both self-provided steam turbine generator sets and the external power grid. Under normal operating conditions, the external power grid provides partial power support to the internal power grid through interconnection lines. When a fault occurs in the external power grid, it is necessary to promptly disconnect the internal power grid from the external power grid and maintain the stable operation of the internal power grid in an isolated manner by disconnecting some non-critical loads and adjusting the operating mode of the generator sets.

[0003] Existing grid-coordinated control systems typically include equipment such as a coordination main control cabinet, a remote data acquisition cabinet, a fault disconnection device, and a turbine digital electro-hydraulic control system. By collecting operating data such as tie line voltage, current, grid disconnection power, circuit breaker status, generator speed, and load shedding status, they determine whether a fault has occurred in the external power grid and execute load shedding and generator regulation control after confirming the disconnection.

[0004] However, in existing technologies, different operational data are typically acquired separately by multiple acquisition devices distributed across substations, generator sets, and load distribution rooms. These data types differ in sampling time, communication transmission time, and data update time. Existing systems usually directly utilize the operational data currently received by the main control cabinet for islanded network assessment, making it difficult to determine whether data from different sources correspond to the same fault event. This can easily lead to misidentification or omission of faults due to voltage fluctuations, communication delays, data lag, or single signal anomalies, impacting the reliability of the enterprise's internal power grid operation.

[0005] Meanwhile, existing load shedding control methods typically determine whether a load has been shedding based on circuit breaker tripping commands or auxiliary contact feedback. However, the circuit breaker position status cannot fully reflect the actual conductivity of the load branch. When there is an abnormality in the circuit breaker auxiliary contacts, unreliable disconnection of the main contacts, or abnormal feedback signals, the system may incorrectly determine that the load has been shedding, resulting in insufficient actual shedding power; or it may continue to perform supplementary load shedding even after the frequency has recovered, causing over-shearing of important loads. Summary of the Invention

[0006] To address the shortcomings of existing grid-machine coordination control methods, such as insufficient time-series correlation capability of multi-source operating data, low accuracy of islanded network identification, and difficulty in accurately confirming the actual load shedding status, this invention provides a grid-machine coordination control method for both internal and external power grids. The method includes: S1. Obtain the operating data of the enterprise's internal power grid, including voltage data, current data, and power data of the external power grid interconnection line, status data of the interconnection line circuit breaker, speed data of the generator set, load power data of the load that can be cut off, and status data of the load that can be cut off. The acquisition time is added to the running data based on a unified clock signal to obtain time-stamped running data. S2. Based on the time-stamped running data, identify candidate trigger signals for isolated networks and obtain the occurrence time of the candidate trigger signals for isolated networks as the event reference time; extract running data whose acquisition time is within the preset verification time range corresponding to the event reference time from the time-stamped running data to obtain the same event running data group, and mark running data whose acquisition time exceeds the preset verification time range, whose time synchronization status is abnormal, or whose communication status is abnormal as invalid running data; S3. Based on the same event operation data group, determine whether the island candidate triggering signal has mutual verification with different types of operation data; if there is mutual verification, determine that a real disconnection event has occurred in the external power grid; if there is no mutual verification, maintain the current operation mode and mark the corresponding island candidate triggering signal as a disturbance signal. S4. When it is determined that a real disconnection event has occurred in the external power grid, control the internal power grid of the enterprise to disconnect from the external power grid, and control the turbine digital electro-hydraulic control system to switch to speed control mode; obtain the power out of the grid before the real disconnection event occurs, and based on the power out of the grid, the load priority and load power of each load that can be disconnected, obtain the first load combination to be disconnected, and send a tripping command to the circuit breaker of the load that can be disconnected corresponding to the first load combination to be disconnected. S5. After sending the tripping command, obtain the tripping feedback data of each switchable load circuit breaker in the first load to be tripped combination and the current change data or load power change data of the corresponding switchable load; based on the tripping feedback data and the current change data or load power change data, obtain the actual tripping status of each switchable load; Based on the confirmed actual shelvable load power before the actual disconnection event, the actual shelving power is obtained; if the actual shelving power does not reach the target shelving power, and the generator speed or the frequency of the enterprise's internal power grid continues to change in the direction of deviating from the rated value, a second load combination to be shelved is obtained from the remaining shelvable loads, and supplementary load shelving is performed on the second load combination to be shelved; if the generator speed or the frequency of the enterprise's internal power grid recovers to the rated value, supplementary load shelving is stopped.

[0007] This invention adds a collection time to the dispersed collection of tie line voltage, current, grid power, circuit breaker status, generator speed, and load shedding status by using a unified clock signal. This enables the main control cabinet to perform event correlation based on the actual time when the operating data is collected on-site, rather than the time it arrives at the main control cabinet. By using the occurrence time of the first isolated network candidate trigger signal as the event reference time and extracting operating data within a preset verification time range from different collection locations, the invention achieves time aggregation of the operating status corresponding to the same physical event, avoiding the combination of sequential and unrelated abnormal data into isolated network conditions.

[0008] Meanwhile, this invention uses a method of cross-verification of different types of operating data to determine whether a real disconnection has occurred in the external power grid. This allows for cross-physical type verification of electrical states such as tie line voltage, current, and power output, mechanical action states such as tie line circuit breaker status, and mechanical response states such as generator speed, improving the error prevention capability of islanded grid judgment. After confirming a real disconnection, the first load combination to be disconnected is selected based on the power output and load priority before the fault occurred, and the turbine digital electro-hydraulic control system is switched to speed control mode, achieving rapid power balance after an external power grid fault.

[0009] This invention also achieves dual confirmation of the mechanical position of the circuit breaker and the actual conductive state of the branch by simultaneously acquiring the tripping feedback data of the load-cutting circuit breaker and the current or load power change data of the corresponding branch. The actual power cut off is calculated by using the actual confirmed load power cut off, which improves the authenticity of the load cutting results. Based on the difference between the actual power cut off and the target power cut off, as well as the direction of change of the generator speed or the internal power grid frequency, it determines whether to perform supplementary load cutting off. This enables the system to make up for the power deficit in a timely manner when the load cutting off is insufficient and the islanded grid frequency continues to decline, and to stop cutting off loads when the frequency has recovered, thereby reducing the risk of insufficient load cutting off and continuous over-cutting.

[0010] Furthermore, the specific steps of S1 include: S101. Based on the acquisition devices installed in the main control cabinet, generator set side equipment, substation remote data acquisition cabinet and load distribution room remote data acquisition cabinet, the operating data is acquired respectively; S102. Set up a clock synchronization device, which includes a Beidou time synchronization module and a GPS time synchronization module. The clock synchronization device sends a unified clock signal to the coordination main control cabinet, the generator set side equipment and each of the remote data acquisition cabinets through at least one of the B code interface, serial communication interface and Ethernet interface. S103. Each of the remote data acquisition cabinets corrects its local time based on the unified clock signal, and when acquiring the running data, adds the corresponding acquisition time, data sequence number, time synchronization status identifier and communication status identifier to each running data. S104. The running data with the acquisition time, data sequence number, time synchronization status identifier and communication status identifier added is used as the time-stamped running data, and the time-stamped running data is sent to the coordination main control cabinet.

[0011] By establishing a unified time reference among the main control cabinet, generator set side equipment, substation remote data acquisition cabinet, and load distribution room remote data acquisition cabinet, time synchronization at different data acquisition locations was achieved. The use of BeiDou and GPS timing modules, along with the transmission of a unified clock signal via B-code, serial communication, or Ethernet interfaces, improved the adaptability and reliability of the time synchronization signal. By simultaneously adding the acquisition time, data sequence number, and time synchronization status identifier to each piece of operational data, the main control cabinet was able to identify the data acquisition time, data transmission continuity, and the validity of the time source, improving the accuracy of operational data validity judgment and providing a reliable data foundation for the subsequent screening of operational data related to the same event.

[0012] Furthermore, the specific steps of S2 include: S201. Set up data buffers corresponding to each source of running data, and store the time-stamped running data in the data buffers in a loop according to the data collection order; S202. At least one of the following is taken as the islanded grid candidate trigger signal: the disconnection signal output by the fault disconnection device, the change signal of the tie line circuit breaker from the closed state to the open state, the tie line low voltage signal, the tie line undercurrent signal, the power change signal of the grid disconnection device, and the generator speed change signal. S203. Obtain the occurrence time of the first occurrence of the candidate trigger signal for the isolated network, and use the occurrence time as the event reference time; S204. Extract time-stamped running data from each of the data buffers, where the time difference between the acquisition time and the event reference time is within the preset verification time range, to obtain the same event running data group. S205. If the time difference between the acquisition time of any running data and the event reference time exceeds the preset verification time range, or if the time synchronization status identifier or communication status identifier corresponding to the running data is in an abnormal state, then the running data is marked as invalid running data, and the invalid running data is not included in the independent judgment of the real disconnection event, the mutual verification of different physical type data, and the calculation of the load combination to be disconnected.

[0013] By setting up data buffers for each remote data acquisition cabinet, continuous storage of operational data before and after the occurrence of an isolated network candidate trigger signal is achieved. The earliest isolated network candidate trigger signal is used to determine the event reference time, and the operational data in each data buffer is extracted with the event reference time as the center. This allows data from different acquisition locations to be recombined according to the same event, improving the time consistency between multi-source operational data. By excluding data that exceeds the preset verification time range, has time synchronization anomalies, or has communication anomalies, the system avoids historical values, out-of-time data, and failed communication data from triggering isolated network operation independently, thus improving the reliability of judging real disconnection events.

[0014] Furthermore, the specific steps of S3 include: S301. Divide the candidate trigger signal of the isolated network into direct disconnection signal and disturbance observation signal; The direct disconnect signal includes the disconnect signal output by the fault disconnect device, and a combined signal formed when the tie line circuit breaker changes from the closed state to the open state and the tie line current drops to a preset current range. The disturbance observation signals include individually occurring low voltage signals, undercurrent signals, sudden power outage signals, circuit breaker position signals, or generator speed change signals. S302. If the same event operation data group contains the direct disconnection signal, and the same event operation data group contains verification data with different physical types, then it is determined that the external power grid has experienced the real disconnection event. S303. If the same event running data group only contains the disturbance observation signal, then determine whether the disturbance observation signal continues to reach the preset confirmation time, and determine whether there is verification data with a different physical type than the disturbance observation signal in the same event running data group. S304. If the disturbance observation signal continues to reach the preset confirmation time and the verification data exists, then it is determined that the external power grid has experienced the actual disconnection event; if the disturbance observation signal does not continue to reach the preset confirmation time or the verification data does not exist, then the disturbance observation signal is marked as the disturbance signal.

[0015] By classifying candidate trigger signals for isolated networks into direct disconnection signals and disturbance observation signals according to their reliability, hierarchical processing of different abnormal states is achieved. Direct disconnection is performed using a combination of fault disconnection signals with higher reliability or circuit breaker tripping and tie line current-free signals, which improves the speed of action under real fault conditions. For individual occurrences of low voltage, undercurrent, power surges, circuit breaker displacement, or speed changes, it is required that they continue to reach a preset confirmation time and be verified by data of different physical types, which reduces the probability of false disconnection caused by short-term disturbances, single measurement point faults, and auxiliary contact jitter, thus balancing the speed and error prevention of disconnection control.

[0016] Furthermore, the verification data for the different physical types includes: Tie line voltage data, tie line current data, and downstream power data are used to reflect the electrical status of the external power grid. Status data of tie line circuit breakers used to reflect the mechanical operating status of switching equipment; And generator set speed data used to reflect the mechanical response status of the generator set; When the candidate trigger signal for the isolated grid belongs to one of the external power grid electrical state, the mechanical action state of the switching equipment, and the mechanical response state of the generator set, the verification data is obtained from at least one of the other two states. If the candidate trigger signal for the isolated network and the verification data both satisfy the corresponding isolated network operation conditions in the same event running data group, then it is determined that the two mutually verify each other.

[0017] By dividing the islanding judgment data into the external power grid electrical state, the mechanical action state of switching equipment, and the mechanical response state of generator sets, cross-verification between different physical processes is achieved. Using data of different physical types from the candidate trigger signals of the islanding as verification data avoids the simultaneous influence of the main criterion and the verification criterion by the same transmitter, the same signal link, or the same type of measurement error, thus improving the independence of islanding judgment. At the same time, it requires that the candidate trigger signals and verification data are located in the same event operation data group, so that the physical type verification and time consistency verification are combined, further improving the accuracy of identifying real disconnection events.

[0018] Furthermore, in step S4, the specific steps for obtaining the first load combination to be cut include: S401. Obtain the power of the network disconnection within a preset time period before the actual disconnection event occurs, and use the power of the network disconnection as the initial power to be disconnected. S402. Obtain the load priority, allowable disconnection status, circuit breaker operating status, communication status, and load power before the event occurs for each of the said disconnectable loads; S403. Remove loads that are lockout priority, have a prohibited disconnection status, are not closed by the circuit breaker, have abnormal communication status, or have no valid load power data from the candidate load set. S404. Select shelvable loads sequentially from the candidate load set according to load priority from low to high; when multiple shelvable loads are included in the same load priority, obtain different load combinations of each shelvable load and their combined power. S405. Select the load combination whose combined power is greater than or equal to the initial power to be cut and whose power difference exceeding the initial power to be cut is the smallest from the different load combinations, and use it as the first load combination to be cut. If the remaining power to be cut is less than the preset load cut-off dead zone, then stop selecting loads to be cut.

[0019] By using the power out of the grid before the actual disconnection event as the initial power to be disconnected, the amount of load to be disconnected can correspond to the actual power supply of the external grid when it suddenly disappears, thus achieving targeted compensation for the power deficit of the islanded grid. By comprehensively considering the load priority, allowable disconnection status, circuit breaker operating status, communication status, and actual load power before the event, loads that are prohibited from being disconnected, cannot be reliably executed, or have invalid operating data are excluded, improving the safety of load selection. By using a power comparison method of different load combinations within the same priority, the load combination with a combined power greater than the initial power to be disconnected and the smallest power difference is selected, thus reducing over-disconnection of loads while covering the power deficit of the islanded grid. By setting a load disconnection dead zone, large complete load branches are avoided from being disconnected to make up for small power differences, improving the rationality of load disconnection control.

[0020] Furthermore, in step S5, the specific steps for obtaining the actual resection state of each shearable load include: S501. When sending a tripping command to any disconnectable load circuit breaker, record the load power of the disconnectable load before the tripping command is sent, and start the corresponding action confirmation time period. S502. During the action confirmation time period, continuously acquire the tripping feedback data of the load-cutting circuit breaker, as well as the branch current or load power of the load-cutting circuit breaker. S503. If the tripping feedback data indicates that the load-disconnectable circuit breaker is in the tripping state, and the branch current or load power drops to the preset residual load range, then the load-disconnectable circuit breaker is marked as successfully disconnected. S504. If the tripping feedback data indicates that the switchable load circuit breaker is in the tripping state, but the branch current or load power has not decreased to the preset residual load range, then the switchable load is marked as a state where the tripping feedback and the conduction state are inconsistent. S505. If the branch current or load power drops to the preset residual load range, but the tripping feedback data indicates that the switchable load circuit breaker is not in the tripping state, then the switchable load is marked as a position feedback abnormal state. S506. If the switchable load circuit breaker is not in the open state and the branch current or load power has not dropped to the preset residual load range, then the switchable load is marked as an actual disconnection failure state.

[0021] By recording the load power and setting an action confirmation time period before sending the tripping command, continuous comparison of the branch operating status before and after load shedding is achieved. By adopting a dual judgment method of circuit breaker tripping feedback and changes in branch current or load power, the load shedding result no longer depends solely on the circuit breaker auxiliary contacts, improving the accuracy of the actual shedding status judgment. By dividing the load shedding result into four states—actual shedding successful, inconsistency between tripping feedback and conduction status, abnormal position feedback, and actual shedding failure—differentiation of different situations such as unreliable disconnection of circuit breaker main contacts, abnormal feedback contacts, abnormal feedback lines, and failure to execute the tripping command is achieved, improving fault location capability and making the display status of the machine-network coordinated control interface closer to the actual field status.

[0022] Furthermore, in step S5, the specific steps for obtaining the actual shearing power and executing the supplementary shearing load include: S601. The power of the shearable load in the actual shearing success state before the actual disconnection event occurs is accumulated to obtain the actual shearing power. S602. Subtract the target cut-off power from the actual cut-off power to obtain the remaining cut-off power; S603. If the remaining power to be cut is greater than the preset load-cutting dead zone, and at least one of the following conditions is met, then based on the remaining power to be cut, the second load combination to be cut is obtained from the remaining loads that can be cut: The generator set speed is below the rated speed and continues to decrease; The internal power grid frequency of the enterprise is below the rated frequency and continues to decline. S604. Send a tripping command to the circuit breaker corresponding to the second load combination to be cut off, and reacquire the actual cut-off power; S605. If the generator set speed or the internal power grid frequency has recovered to the rated value, then the supplementary load shedding shall be stopped, so that the turbine digital electro-hydraulic control system can continue to restore the power balance of the internal power grid through speed regulation.

[0023] By accumulating only the load power of the loads that are successfully disconnected before the actual disconnection event occurs, the actual disconnection power is calculated based on physical confirmation results, avoiding overestimation of the disconnection effect based on tripping commands or planned load combinations. The remaining power to be disconnected is obtained by using the difference between the target disconnection power and the actual disconnection power, and the direction of change in generator speed or internal grid frequency is combined to determine whether to perform supplementary load disconnection. This allows the supplementary disconnection control to reflect both the power difference and the dynamic response of the islanded grid, improving the accuracy of supplementary disconnection decisions. When the frequency continues to drop, the load is promptly disconnected, reducing the risk of low-frequency instability in the islanded grid. When the frequency has recovered to the rated value, the disconnection is stopped, improving the retention rate of important production loads and reducing unnecessary over-disconnection.

[0024] Furthermore, the method also includes: If a communication interruption occurs between any remote data acquisition cabinet and the main control cabinet, or if the data sequence number is continuously missing, or if the update time of the time-stamped running data exceeds the preset data validity time, the corresponding remote data acquisition cabinet will be marked as having a communication abnormality. The fault disconnection signal and key circuit breaker status data input via hard-wiring are retained to participate in the direct disconnection judgment, and the remote operation data corresponding to the abnormal communication status is prohibited from triggering isolated network operation on its own. Based on the abnormal communication status, the remote data acquisition cabinet where the abnormality occurred, the type of operating data affected, and the duration of the abnormality are obtained, and a communication fault alarm message is generated. The communication fault alarm information, the inconsistency between the tripping feedback and the conduction state, the abnormal position feedback state, and the actual disconnection failure state are displayed on the machine-network coordination control interface.

[0025] By comprehensively judging communication interruptions, consecutive missing data sequence numbers, and data update time exceeding limits, the system proactively identifies abnormal communication states of remote data acquisition cabinets. It employs a method that prohibits remote operation data under abnormal communication states from triggering isolated network operation independently, while retaining hard-wired fault disconnection signals and key circuit breaker status for direct disconnection judgment. This avoids malfunctions caused by failed communication data and ensures that key disconnection signals can still participate in control under real fault conditions, improving the system's fault tolerance. Furthermore, by displaying abnormal acquisition cabinets, affected data types, abnormal duration, and different load shedding abnormal states, the system's operational status visualization and fault diagnosis efficiency are improved.

[0026] The present invention also provides an internal and external power grid coordinated control system, the system comprising: Data acquisition unit: used to acquire the operation data of the enterprise's internal power grid, and add the acquisition time to the operation data based on a unified clock signal to obtain time-stamped operation data; Timing verification unit: used to identify candidate triggering signals for isolated networks based on the time-stamped running data, obtain the occurrence time of the candidate triggering signals for isolated networks as the event reference time, extract running data whose acquisition time is within the preset verification time range corresponding to the event reference time from the time-stamped running data, obtain running data groups of the same event, and mark running data whose acquisition time exceeds the preset verification time range, or whose time synchronization status or communication status is abnormal as invalid running data; Island network determination unit: Based on the same event operation data group, it determines whether the island network candidate triggering signals have mutual verification with different types of operation data; if there is mutual verification, it determines that a real disconnection event has occurred in the external power grid; if there is no mutual verification, it maintains the current operation mode and marks the corresponding island network candidate triggering signal as a disturbance signal. Load shedding control unit: When a real disconnection event occurs in the external power grid, it controls the internal power grid of the enterprise to disconnect from the external power grid and controls the turbine digital electro-hydraulic control system to switch to speed control mode; it obtains the power out of the grid before the real disconnection event occurs, and based on the power out of the grid, the load priority and load power of each load that can be shelded, it obtains a first load combination to be shelded, and sends a tripping command to the circuit breaker of the load that can be shelded corresponding to the first load combination to be shelded; The disconnection status confirmation unit is used to obtain the disconnection feedback data of each disconnectable load circuit breaker and the current change data or load power change data of the corresponding disconnectable load after sending the disconnection command. Based on the disconnection feedback data and the current change data or load power change data, it obtains the actual disconnection status of each disconnectable load, and obtains the actual disconnection power based on the load power of the disconnectable load that has been confirmed to be actually disconnected before the actual disconnection event occurs. Supplementary load shedding unit: When the actual shedding power does not reach the target shedding power, and the generator set speed or the frequency of the enterprise's internal power grid continues to change in the direction of deviating from the rated value, it obtains a second load combination to be shedding from the remaining shedding loads and performs supplementary load shedding on the second load combination to be shedding; when the generator set speed and the frequency of the enterprise's internal power grid recover to the rated value, it stops supplementary load shedding.

[0027] The system, its principles, and beneficial effects are similar to those of this method, and will not be elaborated further on this system.

[0028] One or more technical solutions provided by this invention have at least the following technical effects or advantages: 1. This invention adds acquisition time to the operational data at different acquisition locations by using a unified clock signal, and extracts operational data within the same verification time range based on the occurrence time of the candidate trigger signal for the isolated grid. This realizes the same event combination of multi-source operational data, avoids the abnormal states at different times being incorrectly spliced ​​into isolated grid trigger conditions, and improves the accuracy of identifying real disconnection events of the external power grid.

[0029] 2. This invention uses the acquisition time, data sequence number, time synchronization status, and communication status together to determine data validity, thereby enabling the proactive exclusion of historical data, lost data, out-of-time data, and data with communication anomalies. At the same time, it retains the hard-wired key disconnection signal to participate in direct judgment, which improves the system's ability to prevent malfunctions and its fault tolerance in the event of communication anomalies.

[0030] 3. This invention adopts a hierarchical judgment of direct disconnection signal and disturbance observation signal, and requires the disturbance observation signal to be verified by the same event using operating data of different physical types. This realizes cross-verification between electrical status, mechanical status of switchgear and mechanical response status of unit, taking into account both the speed of action during real faults and the prevention of errors during ordinary disturbances.

[0031] 4. This invention selects the load combination to be cut by combining load priority, allowable disconnection status, circuit breaker operating status, communication status and pre-event load power, thereby realizing the active elimination of loads that cannot be cut or are in abnormal status; it adopts the load combination with combined power greater than the power to be cut and the smallest power difference, and sets a load cutting dead zone, which improves the power balancing effect of the islanded network and reduces unnecessary over-cutting of loads.

[0032] 5. This invention achieves physical confirmation of the actual load shedding status through dual verification of circuit breaker tripping feedback and changes in branch current or load power. It can distinguish between states such as actual successful shedding, inconsistency between tripping feedback and conduction status, abnormal position feedback, and actual shedding failure, thereby improving the accuracy of load shedding result judgment and anomaly location.

[0033] 6. This invention uses the actual power of the load that has been confirmed to be actually cut off to calculate the actual power cut off, avoiding the overestimation of the cutting off effect based on the tripping command or planned load combination; by combining the remaining power to be cut off and the direction of the islanded network frequency change to perform supplementary load cutting off, the system can make up for the power deficit in time when the load cutting off is insufficient, and stop cutting off when the frequency has recovered, thereby reducing the risk of low-frequency instability of the islanded network and continuous over-cutting of load.

[0034] 7. This invention displays information such as communication faults, inconsistencies between circuit breaker feedback and conduction status, abnormal position feedback, and actual disconnection failures on the machine-network coordinated control interface, thereby achieving a classified display of the status of communication links, circuit breaker feedback loops, and load branches, improving the visualization of system operation status and the efficiency of fault diagnosis for operators.

[0035] 8. This invention can be configured and upgraded based on existing coordination main control cabinet, remote data acquisition cabinet, fault isolation device, steam turbine digital electro-hydraulic control system, generator excitation system and automatic quasi-synchronization device without changing the main primary wiring structure of the enterprise's internal power grid, thus improving the engineering implementation convenience of the technical solution and the adaptability of existing system transformation. Attached Figure Description

[0036] The accompanying drawings, which are provided to further illustrate embodiments of the invention and constitute a part of this invention, are not intended to limit the scope of the invention. Figure 1 This is a flowchart illustrating a method for coordinated control of internal and external power grids. Detailed Implementation

[0037] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, where there is no conflict, the embodiments of the present invention and the features thereof can be combined with each other.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0039] Example 1 refer to Figure 1 This embodiment provides a method for coordinated control of internal and external power grids, which is applied to the coordinated control between the self-provided generator sets of coking enterprises and the external power grid.

[0040] The grid-machine coordination control system in this embodiment includes a main control cabinet located in the steam turbine electronics room, two remote data acquisition cabinets located in the 35kV substation, one remote data acquisition cabinet located in the methanol power distribution room, and one remote data acquisition cabinet located in the gas turbine power distribution room. The cabinets are connected via fiber optic communication. The main control cabinet can employ a fast main control module, with a processing cycle set to 10ms to meet the real-time requirements for external grid fault diagnosis and rapid load shedding.

[0041] The system also includes a fault isolation device, a turbine digital electro-hydraulic control system (DEH), a generator excitation system, an automatic synchronizing device, an operator station, and a clock synchronization device.

[0042] The fault disconnection device is installed in the 35kV substation and is used to obtain the 35kV bus voltage, tie line current and circuit breaker status. When an external power grid fault is detected, it outputs a disconnection signal to the tie line circuit breaker tripping circuit and the main control cabinet.

[0043] The DEH is used to control the turbine regulating valve. In grid-connected operation, it can be used for valve position control, power control, or main steam pressure control. After the enterprise's internal power grid enters isolated operation, the DEH switches to speed control mode, using the speed regulation loop and fast primary frequency regulation to adjust the opening of the turbine inlet valve, so that the generator speed and the frequency of the enterprise's internal power grid are restored to near the rated value.

[0044] The automatic synchronizing device is installed in the 35kV substation. After the external power grid returns to normal, it outputs speed increase / decrease signals and voltage increase / decrease signals based on the frequency difference, voltage difference, and phase difference between the internal and external power grids. It then coordinates the main control cabinet to send the speed increase / decrease signals to the DEH and the voltage increase / decrease signals to the generator excitation system, ensuring that the internal power grid meets the conditions for synchronous grid connection.

[0045] The method includes the following steps: S1. Obtain the operation data of the enterprise's internal power grid, and add the acquisition time to the operation data based on a unified clock signal to obtain time-stamped operation data; S101. Based on the acquisition devices installed in the main control cabinet, generator set side equipment, 35kV substation remote data acquisition cabinet and load distribution room remote data acquisition cabinet, the operating data is acquired respectively; the operating data includes voltage data, current data and power data of the external power grid tie line, status data of the tie line circuit breaker, speed data of the generator set, load power data of the load that can be cut off, and status data of the load that can be cut off. In this embodiment, the operating data collected by the remote data acquisition cabinet of the 35kV substation may include: active power of the tie line; three-phase voltage of the 35kV bus; three-phase current of the tie line; closing and opening positions of the circuit breaker; disconnection signal output by the fault disconnection device; and status data of the high-voltage or low-voltage side circuit breakers of the three main transformers.

[0046] The operating data collected by the remote data acquisition cabinet in the load distribution room may include: the branch voltage of each shelvable load; the branch current of each shelvable load; the load power obtained based on the branch voltage and branch current; the closing and opening status of each shelvable load circuit breaker; the tripping command output status of each shelvable load circuit breaker; and the status of the permissible disconnection soft pressure plate corresponding to each shelvable load.

[0047] The operating data collected by the generator set side equipment may include: real-time active power of the turbine generator set; turbine speed; turbine speed change rate or speed acceleration; main steam pressure; DEH operating status; turbine regulating valve commands and regulating valve feedback; and generator excitation system operating status.

[0048] S102. Set up a clock synchronization device, which includes a Beidou time synchronization module and a GPS time synchronization module. The clock synchronization device sends a unified clock signal to the coordination main control cabinet, the generator set side equipment and each of the remote data acquisition cabinets through at least one of the B code interface, serial communication interface and Ethernet interface. S103. Each of the remote data acquisition cabinets corrects its local time based on the unified clock signal, and when acquiring the operating data, adds a corresponding acquisition time, data sequence number, time synchronization status identifier and communication status identifier to each operating data. The data sequence number is updated sequentially according to the acquisition order of the same data channel. The time synchronization status identifier is used to indicate whether the corresponding device maintains valid time synchronization, and the communication status identifier indicates whether the data is acquired under normal communication conditions.

[0049] S104. The running data with the acquisition time, data sequence number, time synchronization status identifier and communication status identifier added is used as the time-stamped running data, and the time-stamped running data is sent to the coordination main control cabinet.

[0050] S2. Identify candidate trigger signals for isolated networks and obtain the same event running data group; S201. Set up data buffers corresponding to each source of running data, and store the time-stamped running data in the data buffers in a loop according to the data collection order. When the system is running normally, each data buffer is updated in a loop according to the time order. When the storage space reaches the preset capacity, the earliest running data is overwritten by the newly collected running data.

[0051] S202. At least one of the following signals is used as the islanded grid candidate trigger signal: the disconnection signal output by the fault disconnection device, the change signal of the tie line circuit breaker from closed to open, the tie line low voltage signal, the tie line undercurrent signal, the power surge signal, and the generator speed change signal; for example, during normal grid-connected operation, continuous monitoring is performed: The following conditions are considered: low voltage on the tie line, undercurrent on the tie line, power change in the downstream grid, circuit breaker position change, fault disconnection device output status, and turbine generator speed and acceleration status. When any of these conditions meets the corresponding candidate criteria, it is identified as an islanding candidate trigger signal. More specifically: For example, when the 35kV bus voltage drops to the low voltage criterion range, the low voltage signal is used as a candidate trigger signal for islanding; when the tie line current drops to the undercurrent range, the undercurrent signal is used as a candidate trigger signal for islanding; when the circuit breaker changes from the closed state to the open state, the circuit breaker position change signal is used as a candidate trigger signal for islanding; when the turbine generator speed and speed acceleration meet the corresponding acceleration disconnection conditions, the speed change signal is used as a candidate trigger signal for islanding.

[0052] S203. Obtain the occurrence time of the first occurrence of the candidate trigger signal for the isolated network, and use the occurrence time as the event reference time; S204. Extract time-stamped operating data from each of the data buffers, where the time difference between the acquisition time and the event reference time is within the preset verification time range, to obtain the same event operating data group. The extracted data may include the power output before the event reference time, the bus voltage and tie line current near the event reference time, the circuit breaker status near the event reference time, and the unit speed change status after the event reference time. The above data together form the same event operating data group.

[0053] S205. If the time difference between the acquisition time of any running data and the event reference time exceeds the preset verification time range, or if the time synchronization status identifier or communication status identifier corresponding to the running data is in an abnormal state, then the running data is marked as invalid running data, and the invalid running data is not included in the independent judgment of the real disconnection event, the mutual verification of different physical type data, and the calculation of the load combination to be disconnected.

[0054] For example, if the acquisition time of the low voltage signal is T0, the main control cabinet will obtain the tie line current and circuit breaker status near T0 from the 35kV substation data buffer area, obtain the unit speed and speed acceleration near T0 from the main control cabinet or DEH data buffer area, and obtain the grid power that was in a stable state before T0 from the grid power data buffer area.

[0055] If a certain piece of operational data is still saved as the current value when the main control unit performs the isolated network judgment, but the acquisition time of the operational data is significantly earlier than the event reference time, then the operational data does not belong to this event and cannot be used as an independent basis for this isolated network judgment.

[0056] For example, if a low voltage signal occurs at time T0, but the circuit breaker tripping status currently stored in the main control cabinet is the status generated by a short-term jitter of the auxiliary contact at an earlier time, and the circuit breaker has since been restored to closing, then the tripping status cannot be combined with the low voltage signal at time T0 to determine the disconnection of the external power grid.

[0057] If the time synchronization status of a remote data acquisition cabinet is abnormal, communication is interrupted, or data sequence numbers are discontinuous, the corresponding operating data of that remote data acquisition cabinet will be marked as invalid operating data. Invalid operating data can be used for operator viewing and fault analysis, but must not trigger isolated network operation on its own.

[0058] S3. Determine whether a real disconnection event has occurred in the external power grid: A true disconnection event refers to an event in which different types of operational data in the same event's operational data group are mutually verified, confirming that the external power grid is operating abnormally and has met the preset disconnection conditions, requiring the separation of the enterprise's internal power grid from the external power grid.

[0059] S301. Divide the candidate trigger signal of the isolated network into direct disconnection signal and disturbance observation signal; The direct disconnect signal includes the disconnect signal output by the fault disconnect device, and a combined signal formed when the tie line circuit breaker changes from the closed state to the open state and the tie line current drops to a preset current range. The disturbance observation signals include individually occurring low voltage signals, undercurrent signals, sudden power outage signals, circuit breaker position signals, or generator speed change signals. S302. If the same event operation data group contains the direct disconnection signal, and the same event operation data group contains verification data with different physical types, then it is determined that the external power grid has experienced the real disconnection event. S303. If the same event running data group only contains the disturbance observation signal, then determine whether the disturbance observation signal continues to reach the preset confirmation time, and determine whether there is verification data with a different physical type than the disturbance observation signal in the same event running data group. The verification data for different physical types include: Tie line voltage data, tie line current data, and downstream power data are used to reflect the electrical status of the external power grid. Status data of tie line circuit breakers used to reflect the mechanical operating status of switching equipment; And generator set speed data used to reflect the mechanical response status of the generator set; When the candidate trigger signal for the isolated grid belongs to one of the external power grid electrical state, the mechanical action state of the switching equipment, and the mechanical response state of the generator set, the verification data is obtained from at least one of the other two states. If the candidate trigger signal for the isolated network and the verification data both satisfy the corresponding isolated network operation conditions in the same event running data group, then it is determined that the two mutually verify each other.

[0060] Example: Cross-verification between tie line low voltage signal and circuit breaker status data: Island network candidate trigger signal: Tether line voltage data; Island operation conditions: The tie line voltage is lower than the preset voltage threshold and continues for more than the preset confirmation time.

[0061] For example: Rated tie line voltage: 110kV; Voltage threshold: 70% of rated voltage; Duration: 100ms. That is, if the tie line voltage is <77kV and the duration is >100ms, the low voltage condition is met.

[0062] Verification data: Status data of tie line circuit breakers; Islanded operation conditions: The tie line circuit breaker changes from the closed state to the open state. That is, the circuit breaker state is: closed-open.

[0063] Both appear simultaneously in the same event execution data group: Time range: 10:00:01.000-10:00:01.200; Voltage data: 65kV (below threshold); Circuit breaker status: closed-open.

[0064] It is then assumed that the low voltage signal of the tie line and the circuit breaker tripping status are mutually verified.

[0065] S304. If the disturbance observation signal continues to reach the preset confirmation time and the verification data exists, then it is determined that the external power grid has experienced the actual disconnection event; if the disturbance observation signal does not continue to reach the preset confirmation time or the verification data does not exist, then the disturbance observation signal is marked as the disturbance signal.

[0066] Taking low voltage signals as an example: If the bus voltage drops briefly and then recovers immediately, the tie line current does not disappear, the circuit breaker does not change position, and the unit speed does not change accordingly, then the low voltage signal is identified as a normal voltage disturbance, and grid-connected operation is maintained. If the low voltage on the bus persists and the tie current drops to the undercurrent range within the same event time range, the low voltage signal and the undercurrent signal verify each other. If the low voltage on the busbar persists and the tie line circuit breaker changes from closed to open within the same event time range, the electrical quantities and the mechanical state of the switchgear are mutually verified. If the low voltage on the bus persists, and the unit speed and acceleration indicate that the internal power grid of the enterprise has a mechanical response corresponding to the power loss of the external grid, then the electrical status and the unit's mechanical response mutually verify each other.

[0067] S4. Control the disconnection of internal and external power grids and obtain the first load combination to be shelved: When a real disconnection event is detected in the external power grid, the internal power grid of the enterprise is disconnected from the external power grid, and the digital electro-hydraulic control system of the turbine is switched to speed control mode. That is, after the internal power grid of the enterprise enters islanded operation, the digital electro-hydraulic control system (DEH) switches from valve position control or power control in grid-connected state to speed control mode; the power out of the grid before the real disconnection event occurs is obtained, and based on the power out of the grid, the load priority and load power of each load that can be disconnected, the first load combination to be disconnected is obtained, and a tripping command is sent to the circuit breaker of the load that can be disconnected corresponding to the first load combination to be disconnected. Specifically, in step S4, obtaining the first load combination to be cut includes the following steps: S401. Obtain the power out of the grid within a preset time period before the actual disconnection event occurs, and use the power out of the grid as the initial power to be disconnected; for example, the effective power out of the grid 1 second before the tie line trips can be selected as the initial power to be disconnected.

[0068] S402. Obtain the load priority, allowable disconnection status, circuit breaker operating status, communication status, and load power before the event occurs for each of the said disconnectable loads; S403. Remove loads that are lockout priority, have a prohibited disconnection status, are not closed by the circuit breaker, have abnormal communication status, or have no valid load power data from the candidate load set. S404. Select shelvable loads sequentially from the candidate load set according to load priority from low to high; when multiple shelvable loads are included in the same load priority, obtain different load combinations of each shelvable load and their combined power. S405. Select the load combination whose combined power is greater than or equal to the initial power to be cut and whose power difference exceeding the initial power to be cut is the smallest from the different load combinations, and use it as the first load combination to be cut. For example, if the actual power of three loads that can be cut off within the same priority is 1.2MW, 1.4MW and 1.6MW before the event, and the current remaining power to be cut off is 2.8MW, then the system can choose a load combination of 1.2MW and 1.6MW so that the combined power is equal to 2.8MW; if there is no combination equal to the remaining power to be cut off, then a combination greater than the remaining power to be cut off and with a smaller overcut amount is selected.

[0069] If the remaining power to be cut is less than the preset load cut dead zone, then continue to select loads to be cut to avoid cutting off a large full load branch in order to make up for a small power difference.

[0070] S5. Confirm the actual resection status and determine whether to add resection load: After sending the tripping command, the tripping feedback data of each switchable load circuit breaker in the first load to be tripped combination and the current change data or load power change data of the corresponding switchable load are obtained; based on the tripping feedback data and the current change data or load power change data, the actual tripping status of each switchable load is obtained. Specifically, in step S5, the steps for obtaining the actual resection status of each shearable load include: S501. When sending a tripping command to any disconnectable load circuit breaker, record the load power of the disconnectable load before the tripping command is sent, and start the corresponding action confirmation time period. S502. During the action confirmation time period, continuously acquire the tripping feedback data of the load-cutting circuit breaker, as well as the branch current or load power of the load-cutting circuit breaker. S503. If the tripping feedback data indicates that the switchable load circuit breaker is in the tripped state, and the branch current or load power drops to the preset residual load range, it indicates that both the mechanical position of the circuit breaker and the electrical state of the branch prove that the load has been disconnected. Then, the switchable load is marked as a successfully disconnected state. If the preset residual load range is 0% of the load power before operation, or the branch current is less than 3% of the rated current, and continues to reach the preset stable time.

[0071] S504. If the tripping feedback data indicates that the switchable load circuit breaker is in the tripping state, but the branch current or load power has not dropped to the preset residual load range, it indicates that the position state reflected by the circuit breaker auxiliary contact is inconsistent with the actual conduction state of the branch. Then the switchable load is marked as a state where the tripping feedback and conduction state are inconsistent. S505. If the branch current or load power drops to the preset residual load range, but the tripping feedback data indicates that the switchable load circuit breaker is not in the tripping state, indicating that the branch has lost power, but there may be abnormalities in the circuit breaker auxiliary contacts, feedback lines, DI input channels or related intermediate links, then the switchable load is marked as a position feedback abnormal state. S506. If the switchable load circuit breaker is not in the open state and the branch current or load power has not dropped to the preset residual load range, then the switchable load is marked as an actual disconnection failure state.

[0072] Based on the confirmed actual shelvable load power before the actual disconnection event, the actual shelving power is obtained; if the actual shelving power does not reach the target shelving power, and the generator speed or the frequency of the enterprise's internal power grid continues to change in the direction of deviating from the rated value, a second load combination to be shelved is obtained from the remaining shelvable loads, and supplementary load shelving is performed on the second load combination to be shelved; if the generator speed or the frequency of the enterprise's internal power grid recovers to the rated value, supplementary load shelving is stopped.

[0073] In step S5, the specific steps for obtaining the actual cut-off power and executing the supplementary cut-off load include: S601. The power of the shearable load in the actual shearing success state before the actual disconnection event occurs is accumulated to obtain the actual shearing power. S602. Subtract the target cut-off power from the actual cut-off power to obtain the remaining cut-off power; S603. If the remaining power to be cut is greater than the preset load-cutting dead zone, and at least one of the following conditions is met, then based on the remaining power to be cut, the second load combination to be cut is obtained from the remaining loads that can be cut: The generator set speed is below the rated speed and continues to decrease; The internal power grid frequency of the enterprise is below the rated frequency and continues to decline. S604. Send a tripping command to the circuit breaker corresponding to the second load combination to be cut off, and reacquire the actual cut-off power; S605. If the generator set speed or the internal power grid frequency has recovered to the rated value, then the supplementary load shedding shall be stopped, so that the turbine digital electro-hydraulic control system can continue to restore the power balance of the internal power grid through speed regulation.

[0074] Example 2 Based on Embodiment 1, in this embodiment, the method further includes: If a communication interruption occurs between any remote data acquisition cabinet and the main control cabinet, or if the data sequence number is continuously missing, or if the update time of the time-stamped running data exceeds the preset data validity time, the corresponding remote data acquisition cabinet will be marked as having a communication abnormality. The fault disconnection signal and key circuit breaker status data input via hard-wiring are retained to participate in the direct disconnection judgment, and the remote operation data corresponding to the abnormal communication status is prohibited from triggering isolated network operation on its own. Based on the abnormal communication status, the remote data acquisition cabinet where the abnormality occurred, the type of operating data affected, and the duration of the abnormality are obtained, and a communication fault alarm message is generated. The communication fault alarm information, the inconsistency between the tripping feedback and the conduction state, the abnormal position feedback state, and the actual disconnection failure state are displayed on the machine-network coordination control interface.

[0075] Example 3 Based on the above embodiments, this embodiment also provides an internal and external power grid coordinated control system, the system comprising: Data acquisition unit: used to acquire the operation data of the enterprise's internal power grid, and add the acquisition time to the operation data based on a unified clock signal to obtain time-stamped operation data; Timing verification unit: used to identify candidate triggering signals for isolated networks based on the time-stamped running data, obtain the occurrence time of the candidate triggering signals for isolated networks as the event reference time, extract running data whose acquisition time is within the preset verification time range corresponding to the event reference time from the time-stamped running data, obtain running data groups of the same event, and mark running data whose acquisition time exceeds the preset verification time range, or whose time synchronization status or communication status is abnormal as invalid running data; Island network determination unit: Based on the same event operation data group, it determines whether the island network candidate triggering signals have mutual verification with different types of operation data; if there is mutual verification, it determines that a real disconnection event has occurred in the external power grid; if there is no mutual verification, it maintains the current operation mode and marks the corresponding island network candidate triggering signal as a disturbance signal. Load shedding control unit: When a real disconnection event occurs in the external power grid, it controls the internal power grid of the enterprise to disconnect from the external power grid and controls the turbine digital electro-hydraulic control system to switch to speed control mode; it obtains the power out of the grid before the real disconnection event occurs, and based on the power out of the grid, the load priority and load power of each load that can be shelded, it obtains a first load combination to be shelded, and sends a tripping command to the circuit breaker of the load that can be shelded corresponding to the first load combination to be shelded; The disconnection status confirmation unit is used to obtain the disconnection feedback data of each disconnectable load circuit breaker and the current change data or load power change data of the corresponding disconnectable load after sending the disconnection command. Based on the disconnection feedback data and the current change data or load power change data, it obtains the actual disconnection status of each disconnectable load, and obtains the actual disconnection power based on the load power of the disconnectable load that has been confirmed to be actually disconnected before the actual disconnection event occurs. Supplementary load shedding unit: When the actual shedding power does not reach the target shedding power, and the generator set speed or the frequency of the enterprise's internal power grid continues to change in the direction of deviating from the rated value, it obtains a second load combination to be shedding from the remaining shedding loads and performs supplementary load shedding on the second load combination to be shedding; when the generator set speed and the frequency of the enterprise's internal power grid recover to the rated value, it stops supplementary load shedding.

[0076] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0077] 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 method for coordinated control of internal and external power grids, characterized in that, The method includes: S1. Obtain the operating data of the enterprise's internal power grid, including voltage data, current data, and power data of the external power grid interconnection line, status data of the interconnection line circuit breaker, speed data of the generator set, load power data of the load that can be cut off, and status data of the load that can be cut off. The acquisition time is added to the running data based on a unified clock signal to obtain time-stamped running data. S2. Based on the time-stamped running data, identify candidate trigger signals for isolated networks and obtain the occurrence time of the candidate trigger signals for isolated networks as the event reference time; extract running data whose acquisition time is within the preset verification time range corresponding to the event reference time from the time-stamped running data to obtain the same event running data group, and mark running data whose acquisition time exceeds the preset verification time range, whose time synchronization status is abnormal, or whose communication status is abnormal as invalid running data; S3. Based on the same event operation data group, determine whether the island candidate triggering signal has mutual verification with different types of operation data; if there is mutual verification, determine that a real disconnection event has occurred in the external power grid; if there is no mutual verification, maintain the current operation mode and mark the corresponding island candidate triggering signal as a disturbance signal. S4. When it is determined that a real disconnection event has occurred in the external power grid, control the internal power grid of the enterprise to disconnect from the external power grid, and control the turbine digital electro-hydraulic control system to switch to speed control mode; obtain the power out of the grid before the real disconnection event occurs, and based on the power out of the grid, the load priority and load power of each load that can be disconnected, obtain the first load combination to be disconnected, and send a tripping command to the circuit breaker of the load that can be disconnected corresponding to the first load combination to be disconnected. S5. After sending the tripping command, obtain the tripping feedback data of each switchable load circuit breaker in the first load to be tripped combination and the current change data or load power change data of the corresponding switchable load; based on the tripping feedback data and the current change data or load power change data, obtain the actual tripping status of each switchable load; Based on the confirmed actual shelvable load power before the actual disconnection event, the actual shelving power is obtained; if the actual shelving power does not reach the target shelving power, and the generator speed or the frequency of the enterprise's internal power grid continues to change in the direction of deviating from the rated value, a second load combination to be shelved is obtained from the remaining shelvable loads, and supplementary load shelving is performed on the second load combination to be shelved; if the generator speed or the frequency of the enterprise's internal power grid recovers to the rated value, supplementary load shelving is stopped.

2. The method for coordinated control of internal and external power grids according to claim 1, characterized in that, The specific steps of S1 include: S101. Based on the acquisition devices installed in the main control cabinet, generator set side equipment, substation remote data acquisition cabinet and load distribution room remote data acquisition cabinet, the operating data is acquired respectively; S102. Set up a clock synchronization device, which includes a Beidou time synchronization module and a GPS time synchronization module. The clock synchronization device sends a unified clock signal to the coordination main control cabinet, the generator set side equipment and each of the remote data acquisition cabinets through at least one of the B code interface, serial communication interface and Ethernet interface. S103. Each of the remote data acquisition cabinets corrects its local time based on the unified clock signal, and when acquiring the running data, adds the corresponding acquisition time, data sequence number, time synchronization status identifier and communication status identifier to each running data. S104. The running data with the acquisition time, data sequence number, time synchronization status identifier and communication status identifier added is used as the time-stamped running data, and the time-stamped running data is sent to the coordination main control cabinet.

3. The method for coordinated control of internal and external power grids according to claim 2, characterized in that, The specific steps of S2 include: S201. Set up data buffers corresponding to each source of running data, and store the time-stamped running data in the data buffers in a loop according to the data collection order; S202. At least one of the following is taken as the islanded grid candidate trigger signal: the disconnection signal output by the fault disconnection device, the change signal of the tie line circuit breaker from the closed state to the open state, the tie line low voltage signal, the tie line undercurrent signal, the power change signal of the grid disconnection device, and the generator speed change signal. S203. Obtain the occurrence time of the first occurrence of the candidate trigger signal for the isolated network, and use the occurrence time as the event reference time; S204. Extract time-stamped running data from each of the data buffers, where the time difference between the acquisition time and the event reference time is within the preset verification time range, to obtain the same event running data group. S205. If the time difference between the acquisition time of any running data and the event reference time exceeds the preset verification time range, or if the time synchronization status identifier or communication status identifier corresponding to the running data is in an abnormal state, then the running data is marked as invalid running data, and the invalid running data is not included in the independent judgment of the real disconnection event, the mutual verification of different physical type data, and the calculation of the load combination to be disconnected.

4. The method for coordinated control of internal and external power grids according to claim 3, characterized in that, The specific steps of S3 include: S301. Divide the candidate trigger signal of the isolated network into direct disconnection signal and disturbance observation signal; The direct disconnect signal includes the disconnect signal output by the fault disconnect device, and a combined signal formed when the tie line circuit breaker changes from the closed state to the open state and the tie line current drops to a preset current range. The disturbance observation signals include individually occurring low voltage signals, undercurrent signals, sudden power outage signals, circuit breaker position signals, or generator speed change signals. S302. If the same event operation data group contains the direct disconnection signal, and the same event operation data group contains verification data with different physical types, then it is determined that the external power grid has experienced the real disconnection event. S303. If the same event running data group only contains the disturbance observation signal, then determine whether the disturbance observation signal continues to reach the preset confirmation time, and determine whether there is verification data with a different physical type than the disturbance observation signal in the same event running data group. S304. If the disturbance observation signal continues to reach the preset confirmation time and the verification data exists, then it is determined that the external power grid has experienced the actual disconnection event; if the disturbance observation signal does not continue to reach the preset confirmation time or the verification data does not exist, then the disturbance observation signal is marked as the disturbance signal.

5. The method for coordinated control of internal and external power grids according to claim 4, characterized in that, The verification data for different physical types include: Tie line voltage data, tie line current data, and downstream power data are used to reflect the electrical status of the external power grid. Status data of tie line circuit breakers used to reflect the mechanical operating status of switching equipment; And generator set speed data used to reflect the mechanical response status of the generator set; When the candidate trigger signal for the isolated grid belongs to one of the external power grid electrical state, the mechanical action state of the switching equipment, and the mechanical response state of the generator set, the verification data is obtained from at least one of the other two states. If the candidate trigger signal for the isolated network and the verification data both satisfy the corresponding isolated network operation conditions in the same event running data group, then it is determined that the two mutually verify each other.

6. The method for coordinated control of internal and external power grids according to claim 5, characterized in that, In step S4, the specific steps for obtaining the first load combination to be cut include: S401. Obtain the power of the network disconnection within a preset time period before the actual disconnection event occurs, and use the power of the network disconnection as the initial power to be disconnected. S402. Obtain the load priority, allowable disconnection status, circuit breaker operating status, communication status, and load power before the event occurs for each of the said disconnectable loads; S403. Remove loads that are lockout priority, have a prohibited disconnection status, are not closed by the circuit breaker, have abnormal communication status, or have no valid load power data from the candidate load set. S404. Select shelvable loads sequentially from the candidate load set according to load priority from low to high; when multiple shelvable loads are included in the same load priority, obtain different load combinations of each shelvable load and their combined power. S405. Select the load combination whose combined power is greater than or equal to the initial power to be cut and whose power difference exceeding the initial power to be cut is the smallest from the different load combinations, and use it as the first load combination to be cut. If the remaining power to be cut is less than the preset load cut-off dead zone, then stop selecting loads to be cut.

7. The method for coordinated control of internal and external power grids according to claim 6, characterized in that, In step S5, the specific steps for obtaining the actual resection state of each shearable load include: S501. When sending a tripping command to any disconnectable load circuit breaker, record the load power of the disconnectable load before the tripping command is sent, and start the corresponding action confirmation time period. S502. During the action confirmation time period, continuously acquire the tripping feedback data of the load-cutting circuit breaker, as well as the branch current or load power of the load-cutting circuit breaker. S503. If the tripping feedback data indicates that the load-disconnectable circuit breaker is in the tripping state, and the branch current or load power drops to the preset residual load range, then the load-disconnectable circuit breaker is marked as successfully disconnected. S504. If the tripping feedback data indicates that the switchable load circuit breaker is in the tripping state, but the branch current or load power has not decreased to the preset residual load range, then the switchable load is marked as a state where the tripping feedback and the conduction state are inconsistent. S505. If the branch current or load power drops to the preset residual load range, but the tripping feedback data indicates that the switchable load circuit breaker is not in the tripping state, then the switchable load is marked as a position feedback abnormal state. S506. If the switchable load circuit breaker is not in the open state and the branch current or load power has not dropped to the preset residual load range, then the switchable load is marked as an actual disconnection failure state.

8. The method for coordinated control of internal and external power grids according to claim 7, characterized in that, In step S5, the specific steps for obtaining the actual cut-off power and executing the supplementary cut-off load include: S601. The power of the shearable load in the actual shearing success state before the actual disconnection event occurs is accumulated to obtain the actual shearing power. S602. Subtract the target cut-off power from the actual cut-off power to obtain the remaining cut-off power; S603. If the remaining power to be cut is greater than the preset load-cutting dead zone, and at least one of the following conditions is met, then based on the remaining power to be cut, the second load combination to be cut is obtained from the remaining loads that can be cut: The generator set speed is below the rated speed and continues to decrease; The internal power grid frequency of the enterprise is below the rated frequency and continues to decline. S604. Send a tripping command to the circuit breaker corresponding to the second load combination to be cut off, and reacquire the actual cut-off power; S605. If the generator set speed or the internal power grid frequency has recovered to the rated value, then the supplementary load shedding shall be stopped, so that the turbine digital electro-hydraulic control system can continue to restore the power balance of the internal power grid through speed regulation.

9. The method for coordinated control of internal and external power grids according to claim 8, characterized in that, The method further includes: If a communication interruption occurs between any remote data acquisition cabinet and the main control cabinet, or if the data sequence number is continuously missing, or if the update time of the time-stamped running data exceeds the preset data validity time, the corresponding remote data acquisition cabinet will be marked as having a communication abnormality. The fault disconnection signal and key circuit breaker status data input via hard-wiring are retained to participate in the direct disconnection judgment, and the remote operation data corresponding to the abnormal communication status is prohibited from triggering isolated network operation on its own. Based on the abnormal communication status, the remote data acquisition cabinet where the abnormality occurred, the type of operating data affected, and the duration of the abnormality are obtained, and a communication fault alarm message is generated. The communication fault alarm information, the inconsistency between the tripping feedback and the conduction state, the abnormal position feedback state, and the actual disconnection failure state are displayed on the machine-network coordination control interface.

10. A coordinated control system for internal and external power grids, characterized in that, The system includes: Data acquisition unit: used to acquire the operation data of the enterprise's internal power grid, and add the acquisition time to the operation data based on a unified clock signal to obtain time-stamped operation data; Timing verification unit: used to identify candidate triggering signals for isolated networks based on the time-stamped running data, obtain the occurrence time of the candidate triggering signals for isolated networks as the event reference time, extract running data whose acquisition time is within the preset verification time range corresponding to the event reference time from the time-stamped running data, obtain running data groups of the same event, and mark running data whose acquisition time exceeds the preset verification time range, or whose time synchronization status or communication status is abnormal as invalid running data; Island network determination unit: Based on the same event operation data group, it determines whether the island network candidate triggering signals have mutual verification with different types of operation data; if there is mutual verification, it determines that a real disconnection event has occurred in the external power grid; if there is no mutual verification, it maintains the current operation mode and marks the corresponding island network candidate triggering signal as a disturbance signal. Load shedding control unit: When a real disconnection event occurs in the external power grid, it controls the internal power grid of the enterprise to disconnect from the external power grid and controls the turbine digital electro-hydraulic control system to switch to speed control mode; it obtains the power out of the grid before the real disconnection event occurs, and based on the power out of the grid, the load priority and load power of each load that can be shelded, it obtains a first load combination to be shelded, and sends a tripping command to the circuit breaker of the load that can be shelded corresponding to the first load combination to be shelded; The disconnection status confirmation unit is used to obtain the disconnection feedback data of each disconnectable load circuit breaker and the current change data or load power change data of the corresponding disconnectable load after sending the disconnection command. Based on the disconnection feedback data and the current change data or load power change data, it obtains the actual disconnection status of each disconnectable load, and obtains the actual disconnection power based on the load power of the disconnectable load that has been confirmed to be actually disconnected before the actual disconnection event occurs. Supplementary load shedding unit: When the actual shedding power does not reach the target shedding power, and the generator set speed or the frequency of the enterprise's internal power grid continues to change in the direction of deviating from the rated value, it obtains a second load combination to be shedding from the remaining shedding loads and performs supplementary load shedding on the second load combination to be shedding; when the generator set speed and the frequency of the enterprise's internal power grid recover to the rated value, it stops supplementary load shedding.

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