A grid-connected photovoltaic power station full-station active power over-release emergency limited load control method

Abstract

The application discloses a kind of grid-connected photovoltaic power station whole station active power over-release emergency limit load control method, it is related to grid-connected photovoltaic power station automatic power generation control technical field, the method includes to photovoltaic power station whole station total active power and all photovoltaic power generation unit active power is monitored in real time;The duration of over-release of monitoring whole station total active power is generated corresponding over-release alarm signal according to different over-release duration;According to current being in different over-release alarm period, corresponding emergency limit load strategy control is carried out;When detecting current is in no power limit state, if disconnecting box transformer low-voltage side switch or issuing over-shutdown instruction to power generation unit in previous control stage, then limit load execution degree priority strategy is used to automatically restore box transformer low-voltage side switch and power generation unit.The application constructs limit load control system from monitoring, alarm, control to recovery, realizes the self-recovery of photovoltaic power station under over-release condition, and improves the automation and intelligent level of system operation.

Description

Technical Field

[0001] This invention relates to the field of automatic power generation control technology for grid-connected photovoltaic power plants, and in particular to an emergency load limiting control method for the over-generation of active power in a grid-connected photovoltaic power plant. Background Technology

[0002] Traditional photovoltaic (PV) power plant automatic generation control (AGC) substations automatically adjust active power output according to the active power similarity margin strategy of all generator units in the plant, based on real-time instructions issued by the power system dispatch master station. They also adjust the overall active power output at a certain rate to maintain it within a set range. However, as PV power plant capacity increases, the number of PV power generation units grows, and the network links and hierarchies become more complex, in abnormal situations (such as network failures or PV power generation unit failures), the PV power generation units may become uncontrollable. This could lead to the actual active power output of the entire plant continuously exceeding the target instructions issued by the dispatch master station. Consequently, the AGC substation may fail to meet the requirements of the dispatch master station, affecting the safe and stable operation of the power grid.

[0003] Regarding the situation of continuous over-generation of active power across the entire photovoltaic (PV) power station, the current conventional handling methods are: ① Monitoring the over-generation of active power across the entire PV power station, generating only over-generation alarms, and then manually handling the situation by the power station operation and maintenance personnel. ② In addition to generating over-generation alarms, the 35kV PV collector lines are generally automatically disconnected. Both conventional methods for handling continuous over-generation of active power across the entire PV power station, whether it's just generating over-generation alarms or automatically disconnecting the 35kV PV collector lines, essentially rely on the intervention of the PV power station operation and maintenance personnel. The method of only generating over-generation alarms requires high timeliness from the operation and maintenance personnel, who must intervene manually immediately when an over-generation alarm is generated. The method of automatically disconnecting the 35kV PV collector lines, after resolving the over-generation problem, requires the power station operation and maintenance personnel to take measures to restore the 35kV PV collector lines. In actual PV power station operation, the power station operation and maintenance personnel generally need to first report the disconnection status of the 35kV PV collector lines to the power system dispatch center, and then apply for the restoration of the disconnected 35kV PV collector lines. The reporting and application process following the automatic disconnection of the 35kV photovoltaic power collection line inevitably resulted in economic losses due to time costs.

[0004] Existing over-generation alarm methods are highly dependent on the timeliness of on-site maintenance personnel; if they cannot respond promptly, they are ineffective. Automatically disconnecting 35kV photovoltaic collector lines offers limited control, expands the fault range, fails to provide precise and flexible control, and lacks self-recovery capabilities. To address these issues, there is an urgent need to develop an emergency load limiting control method for active power over-generation across the entire grid-connected photovoltaic power station. Summary of the Invention

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

[0006] Therefore, the problem to be solved by this invention is how to achieve automated, hierarchical, and self-recoverable emergency load limiting control without human intervention when the active power of the entire photovoltaic power station is continuously over-generated, so as to reduce economic losses and improve the safety and flexibility of power station operation.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] In a first aspect, embodiments of the present invention provide a method for emergency load limiting control of active power overload in a grid-connected photovoltaic power station, comprising: real-time monitoring of the total active power of the photovoltaic power station and the active power of all photovoltaic power generation units;

[0009] Monitor the duration of continuous over-generation of the total active power of the entire photovoltaic power station, and generate corresponding over-generation alarm signals based on different over-generation durations;

[0010] Based on the current overload alarm period, implement corresponding emergency load limiting strategies for control;

[0011] When it is detected that the current state is not subject to power restrictions, if the low-voltage side switch of the transformer substation was disconnected or the power generation unit was shut down in the previous control phase, the low-voltage side switch of the transformer substation and the power generation unit will be automatically restored according to the load restriction execution priority strategy.

[0012] As a preferred embodiment of the emergency load limiting control method for the total active power generation of a grid-connected photovoltaic power station as described in this invention, the method includes real-time monitoring of the total active power of the entire photovoltaic power station and the active power of all photovoltaic power generation units, including:

[0013] Real-time acquisition of the actual active power P of the entire photovoltaic power station bReal and the actual active power P of all power generation units iReal Simultaneously, obtain the active power target value P of the entire photovoltaic power station issued by the dispatch center. bGoal The active power target value P allocated by the AGC substation to all power generation units iGoal ; Determining whether the total active power of the entire power station is continuously exceeding the limit: The excess active power deviation value for the total active power of the photovoltaic power station is set as... To prevent oscillations caused by power fluctuations, the reset value after over-generation is set to... And satisfy The over-generation deviation value is set to 1% of the station's rated active power, and the over-generation reset value can be set to 0.8% of the station's rated active power; when At that time, the total active power over-generation signal TS of the entire station will be over-generated. pbo The set position indicates that the total active power of the entire station has entered an over-generation state; when the total active power over-generation signal TS of the entire station is activated... pbo For the position, and At that time, the over-transmission signal TS will be activated. pbo Setting the reset position to 1 indicates that the total active power of the entire station has been restored to normal.

[0014] Evaluating the load limiting execution degree when a power generation unit executes an active power reduction target instruction: for the i-th photovoltaic power generation unit, acquiring the j-th active power target instruction P iGoalj , and the actual active power value P before executing the target instruction iRealj and the actual active power value P' after executing the target instruction iRealj ; setting the active power control precision of the i-th photovoltaic power generation unit as P iCon , wherein the active power control precision represents the minimum executable active power step of the power generation unit, and is set as 0.5% of the rated active power of the power generation unit; when , it indicates that the current period is an active power reduction target instruction period, then the execution degree of the j-th time ; for correction is performed, when , is corrected to 0, that is, when , , which indicates that the actual active power value rises after the power generation unit executes the active power reduction instruction, and the load limiting execution degree of the current time is corrected to 0 at this time; when , is corrected to 1, that is, when , 1, which indicates that the actual active power value after the power generation unit executes the active power reduction instruction is lower than the target value, and the load limiting execution degree of the current time is corrected to 1 at this time, then for the execution degree a multi-time average value is obtained to get the load limiting execution degree of the i-th photovoltaic power generation unit , wherein M is 5 times; the load limiting execution degree the closer to 0, the lower the execution degree when the power generation unit executes the active power reduction target instruction; the load limiting execution degree the closer to 1, the higher the execution degree when the power generation unit executes the active power reduction target instruction.

[0015] As a preferred solution of the emergency load limiting control method for full-station active power overgeneration of a grid-connected photovoltaic power station according to the present invention, the method comprises: monitoring the continuous overgeneration duration of total active power of the whole photovoltaic power station, and generating corresponding overgeneration alarm signals according to different overgeneration durations, comprising:

[0016] accumulating the time scale of the full-station total active power overgeneration signal generated in the monitoring stage, starting timing when the full-station total active power overgeneration signal TS pbo is in closed position, and using t pbo to represent the current continuous overgeneration duration; setting four overgeneration duration stages, which are T1, T2, T3 and T4 respectively, and satisfy T1<T2<T3<T4; when , generating a first-period continuous overgeneration alarm signal TS pboT1 ; when , generating a second-period continuous overgeneration alarm signal TSpboT2 ;when At that time, a third-period continuous over-generation alarm signal TS is generated. pboT3 ;when At that time, a fourth-period continuous over-generation alarm signal TS is generated. pboT4 During any over-issuance period, the over-issuance signal TS pbo When the total active power of the entire station is reset to normal, all time-based over-transmission alarm signals are reset, i.e., TS. pboT1 TS pboT2 TS pboT3 TS pboT4 All are set to quantiles.

[0017] As a preferred embodiment of the emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in this invention, the method includes: implementing corresponding emergency load limiting strategies based on different over-generation alarm periods, including:

[0018] During the first over-generation period, the active power target values ​​of all generating units are proportionally reduced based on the current real-time active power value; when the first period continuous over-generation alarm signal TS is detected... pboT1 When the phase is closed, obtain the actual active power value P of all generating units. iReal Based on the set reduction ratio α, the active power target value for all power generation units is calculated. In the event of sustained over-generation, the overall active power of the station will be reduced proportionally based on the actual generation value of the current generating units; the active power target value will be issued to the generating units. After a certain adjustment period, if the over-generation alarm signal remains in the closed state during the first period, the active power target value of all generating units will be reduced proportionally according to the actual generation value. This adjustment will be repeated M times, while simultaneously satisfying the following conditions: ;

[0019] In the second to fourth over-generation control phases, a priority strategy for load limiting compliance is introduced as the basis for adjustment; during the second over-generation period, priority is given to power generation units with high load limiting compliance, while during the third and fourth over-generation periods, priority is given to power generation units with low load limiting compliance.

[0020] As a preferred embodiment of the emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in this invention, the method further includes: implementing corresponding emergency load limiting strategies based on different over-generation alarm periods;

[0021] During the second over-generation period, a zero-value active power target is issued to the selected generation units according to the load limiting execution priority strategy; a second-period continuous over-generation alarm signal TS is detected. pboT2 When the phase is closed, obtain the actual active power value P of all generating units. iRealand load limit execution degree ;

[0022] When X power generation units are selected, the following conditions are met: When the selection stops, zero active power target values ​​are issued to the selected X generator units. After a certain adjustment period, if the over-generation alarm signal remains active in the second period, the selection is re-sorted according to the load limiting execution priority strategy, from high to low, ensuring that generator units selected in the previous round of adjustment are not selected again. After Y generator units are selected, the following conditions are met: When the selection stops, a zero-value active power target is issued to the selected Y power generation units; this process is repeated multiple times until the actual active power value is reduced to zero by the actual controlled power generation units.

[0023] As a preferred embodiment of the emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in this invention, the method includes: implementing corresponding emergency load limiting strategies based on different over-generation alarm periods; and further includes: when in the third over-generation period, issuing shutdown commands to selected power generation units according to a load limiting execution priority strategy; and detecting a continuous over-generation alarm signal TS for the third period. pboT3 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ;

[0024] When X power generation units are selected, the following conditions are met: When the selection process stops, shutdown commands are issued to the selected X generator units. After a certain adjustment period, if the over-generation alarm signal remains active during the third period, selection is performed again according to the load limiting priority strategy, ensuring that generator units selected in the previous round of adjustment are not selected again. Once Y generator units are selected, the following conditions are met: When the selection stops, a shutdown command is issued to the selected Y power generation units; this process is repeated multiple times until the corresponding number of power generation units stop generating electricity.

[0025] As a preferred embodiment of the emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in this invention, the method further includes: implementing corresponding emergency load limiting strategies based on different over-generation alarm periods;

[0026] When the fourth over-generation period is in progress, the low-voltage side switch of the transformer corresponding to the selected generation unit is disconnected according to the load limiting execution priority strategy; if the fourth period continuous over-generation alarm signal TS is detected... pboT4 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ;

[0027] When X power generation units are selected, the following conditions are met: When the selection stops, a disconnection command is issued to the low-voltage side switch of the transformer corresponding to the selected X generator units; after a certain adjustment time, if the over-generation alarm signal is still in the closed state during the fourth period, the selection is carried out again according to the load limiting execution priority strategy, ensuring that the generator units selected in the previous round of adjustment are not selected again. After Y generator units are selected, the following conditions are met: When the selection stops, a disconnection command is issued to the low-voltage side switch of the transformer corresponding to the selected Y generator units; this process is repeated multiple times until the corresponding number of generator units stop generating electricity.

[0028] During any period of over-generation, when the total active power of the entire station returns to normal, i.e., an over-generation signal TS is detected. pbo When reset, it indicates that the current control strategy has achieved the load limiting effect and exits the control phase; when the main control of the power generation unit fails, the corresponding low-voltage side switch of the transformer substation is controlled to force the power generation unit to shut down.

[0029] As a preferred embodiment of the emergency load limiting control method for active power overload of a grid-connected photovoltaic power station as described in this invention, wherein: when it is detected that the current state is not subject to power limiting, if the low-voltage side switch of the transformer substation was disconnected or a shutdown command was issued to the generator unit during the previous control phase, the low-voltage side switch of the transformer substation and the generator unit are automatically restored according to the load limiting execution priority strategy, including:

[0030] When it is detected that the current state is not subject to power curtailment, if the low-voltage side switch of the transformer substation was disconnected or a shutdown command was issued to the generator unit during the previous control phase, the low-voltage side switch of the transformer substation and the generator unit will be automatically restored according to the load curtailment priority strategy; the actual active power value P of the entire photovoltaic power station will be obtained. bReal The active power target value P of the entire photovoltaic power station issued by the dispatch center. bGoal Set the target active dead zone as P. bDead ;

[0031] when When the actual active power of the entire photovoltaic power station is within the range of the target value plus the target active power dead zone, the active power regulation of the entire photovoltaic power station is in place; the target active power dead zone is set at 0.5% of the rated active power of the entire station, and is activated when the target active power dead zone is detected. And the duration exceeds T ul This means that the total active power of the entire station is currently in an unrestricted power state, and a restoration operation should be performed at this time.

[0032] During the recovery operation, priority is given to restoring generator units that are in a shutdown state but whose corresponding transformer substation low-voltage side switches are in the closed position; firstly, all generator units that are in a shutdown state and whose corresponding transformer substation low-voltage side switches are in the closed position are screened out, and their rated active power P is obtained. jN and load limit execution degree The load shedding execution of power generation units is prioritized based on the load shedding execution rate, from highest to lowest. Power generation units with high load shedding execution rates are given priority for restoration.

[0033] When X power generation units are selected, the following conditions are met: When the selection is complete, stop selecting and issue a start command to the selected generator unit; repeat this process multiple times until all selected generator units have been processed, then select all generator units whose low-voltage side switches of the transformer are in the open position.

[0034] When Y power generation units are selected, the following conditions are met: When the selected generator unit is selected, the selection process stops, and a closing command is sent to the low-voltage side switch of the transformer corresponding to the selected generator unit. This process is repeated multiple times until the total active power of the entire station is no longer in an unlimited load state or a start-up command has been sent to all generator units that are in a shutdown state. A maximum number of generators can be started each time. When the maximum number of generators can be started, the selection process stops, and a start-up waiting time T is set. wait After issuing a power-on command, wait for T wait The system checks the time and determines whether it is still in an unlimited load state. If it is, it continues to execute the power-on recovery logic.

[0035] In a second aspect, embodiments of the present invention provide a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program instructions are executed by the processor, the steps of the emergency load limiting control method for the over-active power generation of the entire grid-connected photovoltaic power station as described in the first aspect of the present invention are implemented.

[0036] Thirdly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, they implement the steps of the emergency load limiting control method for the over-active power generation of the entire grid-connected photovoltaic power station as described in the first aspect of the present invention.

[0037] The beneficial effects of this invention are as follows: By constructing a full-process load limiting control system from monitoring, alarming, control to recovery, this invention achieves autonomous response and self-recovery of photovoltaic power plants under over-generation conditions, significantly reducing manual intervention and improving the automation and intelligence level of system operation. In the event of uncontrolled power generation units, the introduction of low-voltage side switch control in the transformer substation enables rapid isolation of the out-of-control units, effectively preventing the escalation of over-generation risks across the entire station and enhancing the safety protection capabilities of the photovoltaic power plant in emergency situations. By introducing load limiting execution parameters, the invention dynamically selects power generation units with high or low responsiveness to execute load limiting or shutdown commands at different stages, making the control process more targeted and energy-efficient, and improving the overall effectiveness of load limiting regulation. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of 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.

[0039] Figure 1 A flowchart illustrating the emergency load limiting control method for active power over-generation in a grid-connected photovoltaic power station. Figure 2 A flowchart for determining the active power over-generation status of the entire grid-connected photovoltaic power plant during the monitoring phase of the emergency load limiting control method for active power over-generation. Figure 3 A flowchart illustrating the execution of load limiting by power generation units during the monitoring phase of the emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station. Figure 4 A flowchart illustrating the time-segmented over-generation alarm process for the emergency load limiting control method for active power over-generation in a grid-connected photovoltaic power station. Figure 5 A schematic diagram of the active power over-generation signal and the over-generation signals in the first to fourth time periods for the emergency load limiting control method of active power over-generation in grid-connected photovoltaic power plants; Figure 6 The flowchart for the first phase of the over-generation control method in the emergency load limiting control method for active power over-generation of the entire grid-connected photovoltaic power station is shown below. Figure 7 The flowchart for the second phase of the over-generation control method in the emergency load limiting control method for active power over-generation of the entire grid-connected photovoltaic power station is shown below. Figure 8 The flowchart for the third period of the over-generation control method in the emergency load limiting control method for active power over-generation of the entire grid-connected photovoltaic power station is shown below. Figure 9 The flowchart for the fourth period of the over-generation control method in the emergency load limiting control method for active power over-generation of the entire grid-connected photovoltaic power station is shown below. Figure 10 This is a flowchart illustrating the recovery phase of an emergency load limiting control method for over-active power generation in a grid-connected photovoltaic power plant. Detailed Implementation

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] 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 those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0043] Example 1

[0044] Reference Figures 1-10 This is the first embodiment of the present invention, which provides a method for emergency load limiting control of active power over-generation in a grid-connected photovoltaic power station, including:

[0045] S1: Real-time monitoring of the total active power of the entire photovoltaic power station and the active power of all photovoltaic power generation units.

[0046] Furthermore, the actual active power P of the entire photovoltaic power station is collected in real time. bReal and the actual active power P of all power generation units iReal Simultaneously, obtain the active power target value P of the entire photovoltaic power station issued by the dispatch center. bGoal The active power target value P allocated by the AGC substation to all power generation units iGoal ; Determining whether the total active power of the entire power station is continuously exceeding the limit: The excess active power deviation value for the total active power of the photovoltaic power station is set as... To prevent oscillations caused by power fluctuations, the reset value after over-generation is set to... And satisfy The over-generation deviation value is set to 1% of the station's rated active power, and the over-generation reset value can be set to 0.8% of the station's rated active power; when At that time, the total active power over-generation signal TS of the entire station will be over-generated. pbo The set position indicates that the total active power of the entire station has entered an over-generation state; when the total active power over-generation signal TS of the entire station is activated... pbo For the position, and At that time, the over-transmission signal TS will be activated. pbo Setting the reset position to 1 indicates that the total active power of the entire station has been restored to normal.

[0047] Assess the load limiting compliance of the power generation unit when executing the active power reduction target instruction: For the i-th photovoltaic power generation unit, obtain the j-th active power target instruction P iGoalj And the actual active value P before executing the target instruction. iRealj and the actual active value P' after executing the target instructioniRealj Set the active power control accuracy of the i-th photovoltaic power generation unit to P. iCon Active power control accuracy represents the minimum executable active power step size of the power generation unit, set to 0.5% of the rated active power of the power generation unit; when When, it indicates that the current period is in the active power reduction target instruction cycle, then the execution degree of the j-th execution is... ;right Make corrections when At that time, Corrected to 0, that is, when hour, This indicates that when the actual active power value increases after the power generation unit executes the active power reduction command, the current load limiting execution level will be corrected to 0; when At that time, Corrected to 1, that is, when hour, 1 indicates that when the actual active power value is lower than the target value after the power generation unit executes the active power reduction command, the current load limiting execution degree is corrected to 1, and then the execution degree is adjusted accordingly. The load limiting execution degree of the i-th photovoltaic power generation unit is obtained by averaging multiple times. Where M is 5 times; load limit execution degree The closer the value is to 0, the lower the execution rate of the active power reduction target instruction by the power generation unit; the lower the load limiting execution rate. The closer it is to 1, the higher the execution rate of the power generation unit in executing the active power reduction target instruction.

[0048] It should be noted that, as Figure 2 As shown, during the monitoring phase, it is determined whether the total active power of the entire station is continuously exceeding the limit. First, the actual active power value and the target active power value of the entire photovoltaic power station are obtained. Then, it is determined whether the total active power over-generation signal is in the correct position: if the total active power over-generation signal is in the correct position, and the actual active power value is greater than the target active power value plus the over-generation deviation value, then the over-generation signal is in the correct position; if the total active power over-generation signal is in the correct position, and the actual active power value is less than the target active power value plus the over-generation reset value, then the over-generation signal is in the correct position.

[0049] like Figure 3 As shown, during the monitoring phase, the load limiting compliance rate of all generating units is calculated. If the load limiting compliance rate of any unit has not yet been calculated, one unit is selected, and the active power target value and the actual active power value of the previous regulation cycle are obtained. If the active power target value of the previous regulation cycle is less than the actual active power value, the current actual value of the unit is obtained, and the compliance rate of the previous regulation cycle is calculated according to the formula. The calculated compliance rate is corrected, and the average value of M corrected compliance rates is taken. The following example illustrates the calculation process of the load limiting compliance rate of a generating unit.

[0050] Assume that the rated active power of a certain power generation unit is 3MW, and the control accuracy is set to 0.015MW. In the first regulation cycle, the actual output value of the power generation unit is 2.5MW, and the issued target value is 2MW. In the second regulation cycle, the actual output value of the power generation unit is 2.2MW, and the target value of 2MW is issued continuously, and the load limiting execution degree is calculated at this time . In the third regulation cycle, the actual output value of the power generation unit is 2.05MW, and the issued target value is 1.5MW, and the load limiting execution degree is calculated at this time . In the fourth regulation cycle, the actual output value of the power generation unit is 1.8MW, and the issued target value is 1.5MW, and the load limiting execution degree is calculated at this time 45. In the fifth regulation cycle, the actual output value of the power generation unit is 1.6MW, and the issued target value is 1.5MW, and the load limiting execution degree is calculated at this time 66. In the sixth regulation cycle, the actual output value of the power generation unit is 1.5MW, and the issued target value is 1.5MW, and the load limiting execution degree is calculated at this time 1. At this time, calculate the 5-time average load limiting execution degree H= , as shown in Table 1 below:

[0051] Table 1 Statistics of load limiting regulation process and execution degree of power generation unit

[0052]

[0053] S2: Monitor the continuous over-generation duration of the total active power of the entire photovoltaic power station, and generate corresponding over-generation alarm signals according to different over-generation durations.

[0054] Further, accumulate the time scale of the total active over-generation signal of the whole station generated in the monitoring stage, start timing when the total active over-generation signal TS of the whole station is pbo in the closed position, and use t pbo to represent the current continuous over-generation duration; set four over-generation duration stages, which are T1, T2, T3, T4 respectively, and satisfy T1<T2<T3<T4; when , generate the first period continuous over-generation alarm signal TS pboT1 ; when , generate the second period continuous over-generation alarm signal TS pboT2 ; when , generate the third period continuous over-generation alarm signal TS pboT3 ; when , generate the fourth period continuous over-generation alarm signal TS pboT4 ; when in any over-generation period, the over-generation signal TS pbo is reset, that is, when the total active power of the whole station returns to the normal state, all the time-divided over-generation alarm signals are reset, that is, TS pboT1 , TS pboT2 , TSpboT3 TS pboT4 All are set to quantiles.

[0055] It should be noted that, as Figure 4 As shown, during the alarm phase, it is determined whether the station-wide active power over-transmission signal is in the "closed" position: If the station-wide over-transmission signal is in the "closed" position, the duration of the current continuous over-transmission is calculated. If the duration of continuous over-transmission is longer than the duration of the first time period over-transmission, the alarm signal for the first time period is closed. If the duration of continuous over-transmission is longer than the duration of the second time period over-transmission, the alarm signal for the second time period is closed. If the duration of continuous over-transmission is longer than the duration of the third time period over-transmission, the alarm signal for the third time period is closed. If the duration of continuous over-transmission is longer than the duration of the fourth time period over-transmission, the alarm signal for the fourth time period is closed. When the station-wide over-transmission signal is in the "split" position, all time period over-transmission alarm signals are set to the "split" position. The following example illustrates the relationship between the station-wide active power over-transmission signal and the over-transmission signals from the first to the fourth time periods.

[0056] like Figure 5 As shown, during the alarm phase, assume T1 = 60 seconds, T2 = 180 seconds, T3 = 300 seconds, and T4 = 420 seconds. The entire station begins issuing over-signal at 00:00, and at 00:30, the over-signal is reactivated. After 60 seconds, reaching the cumulative judgment time T1, the first over-signal alarm signal TS is issued at 01:30. pboT1 When the over-issuance signal sync time for the entire station lasts for 180 seconds, reaching the T2 cumulative judgment time, the second time period over-issuance alarm signal TS will be triggered at 03:30. pboT2 When the over-issuance signal duration across the entire station reaches the T3 cumulative judgment time after 300 seconds, an over-issuance alarm signal TS will be issued at 05:30 in the third time period. pboT3 When the over-issuance signal duration across the entire station reaches the T4 cumulative judgment time after 420 seconds, the fourth time period over-issuance alarm signal TS will be triggered at 07:30. pboT4 When the over-transmission signal for the entire station is reset at 08:30, all over-transmission signals for the first to fourth time periods are reset.

[0057] S3: Implement corresponding emergency load limiting strategies based on the current overload alarm period.

[0058] Furthermore, during the first over-generation period, the active power target values ​​of all generating units are proportionally reduced based on the current real-time active power value; when a continuous over-generation alarm signal TS for the first period is detected... pboT1 When the phase is closed, obtain the actual active power value P of all generating units. iReal Based on the set reduction ratio α, the active power target value for all power generation units is calculated. In the event of sustained over-generation, the overall active power of the station will be reduced proportionally based on the actual generation value of the current generating units; the active power target value will be issued to the generating units. After a certain adjustment period, if the over-generation alarm signal remains in the closed state during the first period, the active power target value of all generating units will be reduced proportionally according to the actual generation value. This adjustment will be repeated M times, while simultaneously satisfying the following conditions: ;

[0059] In the second to fourth over-generation control phases, a priority strategy for load limiting compliance is introduced as the basis for adjustment; during the second over-generation period, priority is given to power generation units with high load limiting compliance, while during the third and fourth over-generation periods, priority is given to power generation units with low load limiting compliance.

[0060] Furthermore, during the second over-generation period, a zero-value active power target is issued to the selected generation units according to the load limiting execution priority strategy; a second-period continuous over-generation alarm signal TS is detected. pboT2 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ;

[0061] When X power generation units are selected, the following conditions are met: When the selection stops, zero active power target values ​​are issued to the selected X generator units. After a certain adjustment period, if the over-generation alarm signal remains active in the second period, the selection is re-sorted according to the load limiting execution priority strategy, from high to low, ensuring that generator units selected in the previous round of adjustment are not selected again. After Y generator units are selected, the following conditions are met: When the selection stops, a zero-value active power target is issued to the selected Y power generation units; this process is repeated multiple times until the actual active power value is reduced to zero by the actual controlled power generation units.

[0062] Furthermore, during the third over-generation period, a shutdown command is issued to the selected generating units according to the load limiting execution priority strategy; if a continuous over-generation alarm signal TS for the third period is detected... pboT3 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ;

[0063] When X power generation units are selected, the following conditions are met: When the selection process stops, shutdown commands are issued to the selected X generator units. After a certain adjustment period, if the over-generation alarm signal remains active during the third period, selection is performed again according to the load limiting priority strategy, ensuring that generator units selected in the previous round of adjustment are not selected again. Once Y generator units are selected, the following conditions are met: When the selection stops, a shutdown command is issued to the selected Y power generation units; this process is repeated multiple times until the corresponding number of power generation units stop generating electricity.

[0064] Furthermore, during the fourth over-generation period, the low-voltage side switch of the transformer corresponding to the selected power generation unit is disconnected according to the load limiting execution priority strategy; if the fourth period continuous over-generation alarm signal TS is detected... pboT4 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ;

[0065] When X power generation units are selected, the following conditions are met: When the selection stops, a disconnection command is issued to the low-voltage side switch of the transformer corresponding to the selected X generator units; after a certain adjustment time, if the over-generation alarm signal is still in the closed state during the fourth period, the selection is carried out again according to the load limiting execution priority strategy, ensuring that the generator units selected in the previous round of adjustment are not selected again. After Y generator units are selected, the following conditions are met: When the selection stops, a disconnection command is issued to the low-voltage side switch of the transformer corresponding to the selected Y generator units; this process is repeated multiple times until the corresponding number of generator units stop generating electricity.

[0066] During any period of over-generation, when the total active power of the entire station returns to normal, i.e., an over-generation signal TS is detected. pbo When reset, it indicates that the current control strategy has achieved the load limiting effect and exits the control phase; when the main control of the power generation unit fails, the corresponding low-voltage side switch of the transformer substation is controlled to force the power generation unit to shut down.

[0067] It should be noted that, as Figure 6 As shown, during the control phase, if the over-generation alarm signal for the first time period is active and the over-generation alarm signal for the second time period is inactive, then the over-generation load limiting control strategy for the first time period is adopted. The real-time active power of all generating units is obtained. If the maximum number of adjustments has not been reached, the active power target values ​​of all generating units are proportionally reduced according to the actual generation value, based on the reduction ratio coefficient. The following example illustrates the over-generation control process for the first time period.

[0068] Assuming the current total active power of the entire station is 110MW, the target active power is 100MW, the over-generation deviation is set to 1MW, the over-generation correction value is set to 0.8MW, and the reduction ratio is set to 0.9. Assuming there are 5 generating units with current actual generation values ​​of 30MW, 25MW, 25MW, 18MW, and 12MW respectively, the first adjustment will issue target values ​​of 27MW, 22.5MW, 22.5MW, 16.2MW, and 10.8MW to the 5 generating units respectively. During the second adjustment, the actual generation values ​​of the 5 generating units are 29MW, 24MW, 24MW, 17MW, and 11MW, and the total active power of the station is 105MW. It is determined that the station is still in an over-generation state and adjustment continues. The second adjustment will issue target values ​​of 26.1MW, 21.6MW, 21.6MW, 15.3MW, and 9.9MW to the 5 generating units respectively. During the third adjustment, the actual power generation values ​​of the five generating units were 28MW, 23MW, 23MW, 16MW, and 10MW, respectively, with a total active power of 100MW for the entire station. It was determined that the over-generation state had been exited, and the load-limiting adjustment was completed, as shown in Table 2 below:

[0069] Table 2 Comparison of Active Power Values ​​Adjusted in Each Generation Unit

[0070]

[0071] like Figure 7 As shown, during the control phase, if the over-generation alarm signals for the first and second time periods are combined, and the over-generation alarm signals for the third time period are separate, then the over-generation load limiting control strategy for the second time period is adopted. The real-time active power of all current generating units is obtained. If the maximum number of adjustments has not been reached, a load limiting execution priority strategy is adopted, and generating units are sorted from high to low according to their load limiting execution degree. One generating unit is selected, and the real-time active power values ​​of all currently selected generating units are accumulated. When the accumulated real-time active power values ​​of all selected generating units exceed the total station's actual active power generation value minus the total station's active power target value plus the active power over-generation reset value, the selection of generating units is stopped, and a zero-value active power target value is issued to all selected generating units; otherwise, the selection of generating units continues. The following example illustrates the over-generation control process for the second time period.

[0072] Assume the current total active power of the entire station is 20MW, the target active power value is 10MW, the over-generation deviation is set to 1MW, and the over-generation reset value is set to 0.8MW. Assume there are 5 generating units, each currently generating 4MW, with their load limit compliance rates ranked from highest to lowest as 0.95, 0.80, 0.70, 0.50, and 0.40. During the first adjustment, the three generating units with load limit compliance rates of 0.95, 0.80, and 0.70 are selected, satisfying the condition 4+4+4>20-(10+0.8), and a zero active power target value is issued to these selected generating units. During the second adjustment, it is possible that the actual active power value of generating units with load limit compliance rates of 0.95 and 0.80 is zero, but the actual active power value of generating unit with a load limit compliance rate of 0.7 is still 4MW. In this case, the total active power of the entire station is 12MW, and the station remains in an over-generation state, requiring further adjustment. The currently selected generating units will not be selected again. The selected generating unit will have a load limit compliance rate of 0.5, satisfying 4 > 12 - (10 + 0.8). A zero active power target value will be issued to the selected generating unit. During the third adjustment, the actual active power value of the generating unit with a load limit compliance rate of 0.5 will be zero. At this point, the total active power of the entire station will be 8MW, no longer in an over-generation state. The load limit adjustment will then end, as shown in Table 3 below. Table 3 Load Limitation Execution and Active Power Response of Each Generation Unit

[0073]

[0074] like Figure 8As shown, during the control phase, if the over-generation alarm signals for the first, second, and third time periods are combined, and the over-generation alarm signal for the fourth time period is separated, then the over-generation load limiting control strategy for the third time period is adopted. The real-time active power of all current generating units is obtained. If the maximum number of adjustments has not been reached, a load limiting execution priority strategy is adopted, sorting generating units according to their load limiting execution degree from low to high. One generating unit is selected, and the real-time active power values ​​of all currently selected generating units are accumulated. When the accumulated real-time active power values ​​of all selected generating units exceed the total station's actual active power generation value minus the total station's active power target value plus the active power over-generation reset value, the selection of generating units is stopped, and a shutdown command is issued to all selected generating units; otherwise, the selection of generating units continues. In the over-generation control of the third and fourth time periods, the load limiting execution degree of generating units is sorted from low to high, prioritizing the shutdown of generating units with low load limiting execution degrees, unlike the second time period over-generation control where the load limiting execution degree of individual generating units is sorted from high to low, prioritizing generating units with high load limiting execution degrees. The second-stage over-generation control essentially requires the generating units to execute a zero-value active power target. In this case, selecting generating units with higher controllability is more beneficial for them to proactively reduce their active power to zero. The third and fourth-stage over-generation control uses different methods to shut down the generating units. In these cases, selecting generating units with lower controllability avoids wasting the execution opportunities of controllable generating units and facilitates the subsequent recovery process. The following example illustrates the third-stage over-generation control process.

[0075] Assume the current total active power of the entire station is 20MW, the target active power is 10MW, the over-generation deviation is set to 1MW, and the over-generation reset value is set to 0.8MW. Assume there are 5 generating units, each currently generating 4MW, with their load limit compliance rates ranked from smallest to largest as 0.2, 0.4, 0.6, 0.8, and 0.9. During the first adjustment, the three generating units with load limit compliance rates of 0.2, 0.4, and 0.6 are selected, satisfying the condition 4+4+4>20-(10+0.8), and a shutdown remote control command is issued to these selected generating units. During the second adjustment, it is possible that generating units with load limit compliance rates of 0.2 and 0.4 have been shut down, but the generating unit with a load limit compliance rate of 0.6 still has an actual active power of 4MW. In this case, the total active power of the entire station is 12MW, and the station remains in an over-generation state, requiring further adjustment. The currently selected generating units are no longer selected. The generating unit with a load limit compliance rate of 0.8 is selected, satisfying 4>12-(10+0.8). A shutdown remote control command is issued to the selected generating unit. During the third adjustment, the generating unit with a load limit compliance rate of 0.8 has been shut down. At this point, the total active power of the entire station is 8MW, no longer in an over-generating state. The load limit adjustment is complete, as shown in Table 4 below:

[0076] Table 4. Hierarchical Shutdown Adjustment Process and Active Power Response Based on Load Limit Execution Level

[0077]

[0078] like Figure 9 As shown, during the control phase, if the over-generation alarm signals for the first, second, third, and fourth time periods are all in the closed position, the over-generation load limiting control strategy for the fourth time period is adopted. The real-time active power of all current generating units is obtained. If the maximum number of adjustments has not been reached, a load limiting execution priority strategy is adopted, sorting the generating units according to their execution degree from low to high. One generating unit is selected, and the real-time active power values ​​of all currently selected generating units are accumulated. When the accumulated real-time active power values ​​of all selected generating units exceed the total station's actual active power value minus the total station's active power target value plus the active power over-generation reset value, the selection of generating units is stopped, and a disconnect command is issued to the low-voltage side switches of the corresponding transformer substations for all selected generating units; otherwise, the selection of generating units continues. The logic of the fourth-time over-generation control process is similar to that of the third-time over-generation control process. The biggest difference is that when the generating unit itself cannot be shut down, an external means is introduced to force shutdown by disconnecting the low-voltage side switches of the corresponding transformer substation. The fourth-time over-generation control is a powerful supplement to the third-time over-generation control, providing redundancy and ensuring the final completion of load limiting.

[0079] S4: When it is detected that the current state is not subject to power restriction, if the low-voltage side switch of the transformer substation was disconnected or the power generation unit was shut down in the previous control phase, the low-voltage side switch of the transformer substation and the power generation unit will be automatically restored according to the load restriction execution priority strategy.

[0080] Furthermore, when it is detected that the current state is not subject to power curtailment, if the low-voltage side switch of the transformer substation was disconnected or a shutdown command was issued to the generator unit during the previous control phase, the low-voltage side switch of the transformer substation and the generator unit will be automatically restored according to the load curtailment priority strategy; the actual active power value P of the entire photovoltaic power station will be obtained. bReal The active power target value P of the entire photovoltaic power station issued by the dispatch center. bGoal Set the target active dead zone as P. bDead ;

[0081] when When the actual active power of the entire photovoltaic power station is within the range of the target value plus the target active power dead zone, the active power regulation of the entire photovoltaic power station is in place; the target active power dead zone is set at 0.5% of the rated active power of the entire station, and is activated when the target active power dead zone is detected. And the duration exceeds T ul This means that the total active power of the entire station is currently in an unrestricted power state, and a restoration operation should be performed at this time.

[0082] During the recovery operation, priority is given to restoring generator units that are in a shutdown state but whose corresponding transformer substation low-voltage side switches are in the closed position; firstly, all generator units that are in a shutdown state and whose corresponding transformer substation low-voltage side switches are in the closed position are screened out, and their rated active power P is obtained. jNand load limit execution degree The load shedding execution of power generation units is prioritized based on the load shedding execution rate, from highest to lowest. Power generation units with high load shedding execution rates are given priority for restoration.

[0083] When X power generation units are selected, the following conditions are met: When the selection is complete, stop selecting and issue a start command to the selected generator unit; repeat this process multiple times until all selected generator units have been processed, then select all generator units whose low-voltage side switches of the transformer are in the open position.

[0084] When Y power generation units are selected, the following conditions are met: When the selected generator unit is selected, the selection process stops, and a closing command is sent to the low-voltage side switch of the transformer corresponding to the selected generator unit. This process is repeated multiple times until the total active power of the entire station is no longer in an unlimited load state or a start-up command has been sent to all generator units that are in a shutdown state. A maximum number of generators can be started each time. When the maximum number of generators can be started, the selection process stops, and a start-up waiting time T is set. wait After issuing a power-on command, wait for T wait The system checks the time and determines whether it is still in an unlimited load state. If it is, it continues to execute the power-on recovery logic.

[0085] It should be noted that, as Figure 10 As shown, during the recovery phase, if the total active power over-generation signal is in the 1 / 2 position and the total active power is detected to be in an unrestricted load state, a recovery operation is performed if any generating units and their corresponding transformer low-voltage side switches have not returned to normal. First, it is determined whether there are generating units in a shutdown state with their corresponding transformer low-voltage side switches in the closed position. If so, these generating units are selected and sorted from highest to lowest according to their load-limiting compliance. One selected generating unit is chosen, and the rated active power of all currently selected generating units is accumulated. If the accumulated rated active power of all selected generating units exceeds the total station active power target value minus the total station active power actual generation value, a start-up command is issued to all selected generating units. If it is determined that there are no generator units in the shutdown state with the corresponding low-voltage side switch of the transformer substation in the closed position, then it is determined whether there are generator units in the shutdown state with the corresponding low-voltage side switch of the transformer substation in the open position. If so, the generator units in the shutdown state with the corresponding low-voltage side switch of the transformer substation in the open position are selected and sorted from high to low according to the load limiting compliance. One of the selected generator units is selected, and the rated active power of all currently selected generator units is accumulated. If the accumulated rated active power of all selected generator units is greater than the total active power target value minus the total active power generation value of the entire station, then a closing command is issued to the low-voltage side switch of the transformer substation corresponding to the selected generator unit. The following example illustrates the control process during the recovery phase.

[0086] Assuming the station has entered an unrestricted power state after load limiting control is completed, the total active power of the entire station is 10MW, and the target active power value is 25MW. Assume the maximum number of generators that can be started is 2, and the start-up waiting time is 2 minutes. Assume 5 generator units are in a shutdown state, of which 3 generator units are shut down but their corresponding transformer low-voltage side switches are closed, and the corresponding transformer low-voltage side switches of the 2 generator units are open. Assume the rated active power of each of the 5 generator units is 4MW. The load limiting compliance rates of the 3 shut-down generator units, from highest to lowest, are 0.9, 0.8, and 0.6; the load limiting compliance rates of the 2 generator units with open transformer low-voltage side switches, from highest to lowest, are 0.4 and 0.2. During the first adjustment, the shut-down generator units with closed transformer low-voltage side switches are prioritized. Considering both the maximum number of generators that can be started and the difference between the actual power generation and the target value, the two generator units with load limiting compliance rates of 0.9 and 0.8 are selected to issue start-up commands. After a 2-minute start-up waiting period, assuming both generator units successfully start up and accept the new target value, their actual active power is 2MW each. The total active power of the entire station is 14MW, indicating it is still in an unrestricted power condition. At this point, the generator unit with the low-voltage side switch closed is prioritized for shutdown, and a start-up command is issued to the generator unit with a load limit execution degree of 0.6. After another 2-minute start-up waiting period, assuming the second generator unit successfully starts up and accepts the new target command, its actual active power is 2MW, indicating the total active power of the entire station is 16MW, indicating it is still in an unrestricted power condition. At this point, the generator unit with the low-voltage side switch open is selected, and generator units with load limit execution degrees of 0.4 and 0.2 are selected, and a closing command is issued to the corresponding low-voltage side switch of the transformer substation. After another 2-minute start-up waiting period, assuming the third generator unit successfully closes the low-voltage side switch of the transformer substation, the total active power of the entire station is 16MW, indicating it is in an unrestricted power condition. At this point, generator units with load limit execution degrees of 0.4 and 0.2 are selected, and a start-up command is issued. After a 2-minute startup waiting period, assuming the fourth adjustment of the power generation unit successfully starts up, all power generation units will return to normal status, and the recovery logic will exit, as shown in Table 5 below:

[0087] Table 5. Sequential Restoration and Regulation Process of Generating Units and Active Power Changes of the Entire Station During the Load Limit Relief Phase

[0088]

[0089] This embodiment also provides a computer device applicable to the emergency load limiting control method for the active power overload of a grid-connected photovoltaic power station, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the emergency load limiting control method for the active power overload of a grid-connected photovoltaic power station as proposed in the above embodiment.

[0090] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0091] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the emergency load limiting control method for the entire active power over-generation of a grid-connected photovoltaic power station as proposed in the above embodiment.

[0092] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for emergency load limiting control of active power overload in a grid-connected photovoltaic power station, characterized in that, include: Real-time monitoring of the total active power of the entire photovoltaic power station and the active power of all photovoltaic power generation units; Monitor the duration of continuous over-generation of the total active power of the entire photovoltaic power station, and generate corresponding over-generation alarm signals based on different over-generation durations; Based on the current overload alarm period, implement corresponding emergency load limiting strategies for control; When it is detected that the current state is not subject to power restrictions, if the low-voltage side switch of the transformer substation was disconnected or the power generation unit was given a shutdown command during the previous control phase, the low-voltage side switch of the transformer substation and the power generation unit will be automatically restored according to the load restriction execution priority strategy. The real-time monitoring of the total active power of the entire photovoltaic power station and the active power of all photovoltaic power generation units includes: Real-time acquisition of the actual active power P of the entire photovoltaic power station bReal and the actual active power P of all power generation units iReal Simultaneously, obtain the active power target value P of the entire photovoltaic power station issued by the dispatch center. bGoal The active power target value P allocated by the AGC substation to all power generation units iGoal ; Determining whether the total active power of the entire power station is continuously exceeding the limit: The excess active power deviation value for the total active power of the photovoltaic power station is set as... To prevent oscillations caused by power fluctuations, the reset value after over-generation is set to... And satisfy The over-generation deviation value is set to 1% of the station's rated active power, and the over-generation reset value can be set to 0.8% of the station's rated active power; when At that time, the total active power over-generation signal TS of the entire station will be over-generated. pbo The set position indicates that the total active power of the entire station has entered an over-generation state; when the total active power over-generation signal TS of the entire station is activated... pbo For the position, and At that time, the over-transmission signal TS will be activated. pbo Setting the reset position to 1 indicates that the total active power of the entire station has been restored to normal. Assess the load limiting compliance of the power generation unit when executing the active power reduction target instruction: For the i-th photovoltaic power generation unit, obtain the j-th active power target instruction P iGoalj And the actual active value P before executing the target instruction. iRealj and the actual active value P' after executing the target instruction iRealj Set the active power control accuracy of the i-th photovoltaic power generation unit to P. iCon Active power control accuracy represents the minimum executable active power step size of the power generation unit, set to 0.5% of the rated active power of the power generation unit; when When, it indicates that the current period is in the active power reduction target instruction cycle, then the execution degree of the j-th execution is... ;right Make corrections when At that time, Corrected to 0, that is, when hour, This indicates that when the actual active power value increases after the power generation unit executes the active power reduction command, the current load limiting execution level will be corrected to 0; when At that time, Corrected to 1, that is, when hour, This indicates that when the actual active power value is lower than the target value after the power generation unit executes the active power reduction command, the current load limiting execution degree is corrected to 1, and then the execution degree is adjusted accordingly. The load limiting execution degree of the i-th photovoltaic power generation unit is obtained by averaging multiple times. Where M is 5 times; load limit execution degree The closer the value is to 0, the lower the execution rate of the active power reduction target instruction by the power generation unit; the lower the load limiting execution rate. The closer it is to 1, the higher the execution rate of the power generation unit in executing the active power reduction target instruction.

2. The emergency load limiting control method for active power overload of a grid-connected photovoltaic power station as described in claim 1, characterized in that: The monitoring system tracks the duration of continuous over-generation of the total active power of the entire photovoltaic power station, and generates corresponding over-generation alarm signals based on different over-generation durations, including: accumulation on the time scale of the total active power over-generation signal of the whole station generated in the monitoring stage, when the total active power over-generation signal TS of the whole station pbo is in the closed position, timing starts, and t pbo represents the current duration of continuous over-generation; four over-generation duration stages are set, which are T1, T2, T3, T4 respectively, and satisfy T1<T2<T3<T4; when a first-period continuous over-generation alarm signal TS is generated pboT1 ; when a second-period continuous over-generation alarm signal TS is generated pboT2 ; when a third-period continuous over-generation alarm signal TS is generated pboT3 ; when a fourth-period continuous over-generation alarm signal TS is generated pboT4 ; when in any over-generation period, the over-generation signal TS pbo is reset, that is, the total active power of the whole station returns to the normal state, all the time-divided over-generation alarm signals are reset, that is, TS pboT1 , TS pboT2 , TS pboT3 , TS pboT4 are all set to open position.

3. The emergency load limiting control method for active power overload of a grid-connected photovoltaic power station as described in claim 2, characterized in that: The emergency load limiting strategy control based on different overload alarm periods includes: During the first over-generation period, the active power target values ​​of all generating units are proportionally reduced based on the current real-time active power value; when the first period continuous over-generation alarm signal TS is detected... pboT1 When the phase is closed, obtain the actual active power value P of all generating units. iReal Based on the set reduction ratio α, the active power target value for all power generation units is calculated. In the event of sustained over-generation, the overall active power of the station will be reduced proportionally based on the actual generation value of the current generating units; the active power target value will be issued to the generating units. After a certain adjustment period, if the over-generation alarm signal remains in the closed state during the first period, the active power target value of all generating units will be reduced proportionally according to the actual generation value. This adjustment will be repeated M times, while simultaneously satisfying the following conditions: ; In the second to fourth over-generation control phases, a priority strategy for load limiting compliance is introduced as the basis for adjustment; during the second over-generation period, priority is given to power generation units with high load limiting compliance, while during the third and fourth over-generation periods, priority is given to power generation units with low load limiting compliance.

4. The emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in claim 2, characterized in that, The method of implementing corresponding emergency load limiting strategies based on different overload alarm periods also includes: During the second over-generation period, a zero-value active power target is issued to the selected generation units according to the load limiting execution priority strategy; a second-period continuous over-generation alarm signal TS is detected. pboT2 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ; When X power generation units are selected, the following conditions are met: When the selection stops, zero active power target values ​​are issued to the selected X generator units. After a certain adjustment period, if the over-generation alarm signal remains active in the second period, the selection is re-sorted according to the load limiting execution priority strategy, from high to low, ensuring that generator units selected in the previous round of adjustment are not selected again. After Y generator units are selected, the following conditions are met: When the selection stops, a zero-value active power target is issued to the selected Y power generation units; this process is repeated multiple times until the actual active power value is reduced to zero by the actual controlled power generation units.

5. The emergency load limiting control method for active power overload of a grid-connected photovoltaic power station as described in claim 2, characterized in that: The method of implementing corresponding emergency load limiting strategies based on different overload alarm periods also includes: When the third over-generation period is in progress, a shutdown command is issued to the selected generating unit according to the load limiting execution priority strategy; if the third period continuous over-generation alarm signal TS is detected... pboT3 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ; When X power generation units are selected, the following conditions are met: When the selection process stops, shutdown commands are issued to the selected X generator units. After a certain adjustment period, if the over-generation alarm signal remains active during the third period, selection is performed again according to the load limiting priority strategy, ensuring that generator units selected in the previous round of adjustment are not selected again. Once Y generator units are selected, the following conditions are met: When the selection stops, a shutdown command is issued to the selected Y power generation units; this process is repeated multiple times until the corresponding number of power generation units stop generating electricity.

6. The emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in claim 2, characterized in that: The method of implementing corresponding emergency load limiting strategies based on different overload alarm periods also includes: When the fourth over-generation period is in progress, the low-voltage side switch of the transformer corresponding to the selected generation unit is disconnected according to the load limiting execution priority strategy; if the fourth period continuous over-generation alarm signal TS is detected... pboT4 When the phase is closed, obtain the actual active power value P of all generating units. iReal and load limit execution degree ; When X power generation units are selected, the following conditions are met: When the selection stops, a disconnection command is issued to the low-voltage side switch of the transformer corresponding to the selected X generator units; after a certain adjustment time, if the over-generation alarm signal is still in the closed state during the fourth period, the selection is carried out again according to the load limiting execution priority strategy, ensuring that the generator units selected in the previous round of adjustment are not selected again. After Y generator units are selected, the following conditions are met: When the selection stops, a disconnection command is issued to the low-voltage side switch of the transformer corresponding to the selected Y generator units; this process is repeated multiple times until the corresponding number of generator units stop generating electricity. During any period of over-generation, when the total active power of the entire station returns to normal, i.e., an over-generation signal TS is detected. pbo When reset, it indicates that the current control strategy has achieved the load limiting effect and exits the control phase; when the main control of the power generation unit fails, the corresponding low-voltage side switch of the transformer substation is controlled to force the power generation unit to shut down.

7. The method for emergency load limiting control of active power overload in a grid-connected photovoltaic power station as described in claim 1, characterized in that: When it is detected that the current state is not subject to power limiting, if the low-voltage side switch of the transformer substation was disconnected or a shutdown command was issued to the generator unit during the previous control phase, the low-voltage side switch of the transformer substation and the generator unit will be automatically restored according to the load limiting execution priority strategy, including: When it is detected that the current state is not subject to power curtailment, if the low-voltage side switch of the transformer substation was disconnected or a shutdown command was issued to the generator unit during the previous control phase, the low-voltage side switch of the transformer substation and the generator unit will be automatically restored according to the load curtailment priority strategy; the actual active power value P of the entire photovoltaic power station will be obtained. bReal The active power target value P of the entire photovoltaic power station issued by the dispatch center. bGoal Set the target active dead zone as P. bDead ; when When the actual active power of the entire photovoltaic power station is within the range of the target value plus the target active power dead zone, the active power regulation of the entire photovoltaic power station is in place; the target active power dead zone is set at 0.5% of the rated active power of the entire station, and is activated when the target active power dead zone is detected. And the duration exceeds T ul This means that the total active power of the entire station is currently in an unrestricted power state, and a restoration operation should be performed at this time. During the recovery operation, priority is given to restoring generator units that are in a shutdown state but whose corresponding transformer substation low-voltage side switches are in the closed position; firstly, all generator units that are in a shutdown state and whose corresponding transformer substation low-voltage side switches are in the closed position are screened out, and their rated active power P is obtained. jN and load limit execution degree The load shedding execution of power generation units is prioritized based on the load shedding execution rate, and power generation units with high load shedding execution rates are given priority for restoration. When X power generation units are selected, the following conditions are met: When the selection is complete, stop selecting and issue a start command to the selected generator unit; repeat this process multiple times until all selected generator units have been processed, then select all generator units whose low-voltage side switches of the transformer are in the open position. When Y power generation units are selected, the following conditions are met: When the selected generator unit is selected, the selection process stops, and a closing command is sent to the low-voltage side switch of the transformer corresponding to the selected generator unit. This process is repeated multiple times until the total active power of the entire station is no longer in an unlimited load state or a start-up command has been sent to all generator units that are in a shutdown state. A maximum number of generators can be started each time. When the maximum number of generators can be started, the selection process stops, and a start-up waiting time T is set. wait After issuing a power-on command, wait for T wait The system checks the time and determines whether it is still in an unlimited load state. If it is, it continues to execute the power-on recovery logic.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the emergency load limiting control method for the entire active power over-generation of a grid-connected photovoltaic power station as described in any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the emergency load limiting control method for the active power over-generation of the entire grid-connected photovoltaic power station as described in any one of claims 1 to 7.

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