Active power over-power emergency load limiting control method for whole grid-connected photovoltaic power station

Abstract

The invention discloses a grid-connected photovoltaic power station total-station active power over-generation emergency load limiting control method, and relates to the technical field of grid-connected photovoltaic power station automatic power generation control, and the method comprises the steps: carrying out the real-time monitoring of the total active power of a photovoltaic power station total station and the active power of all photovoltaic power generation units; monitoring the continuous over-transmission duration of the total active power of the whole station, and generating corresponding over-transmission alarm signals according to different over-transmission durations; corresponding emergency load limiting strategy control is carried out according to different over-sending alarm time periods at present; and when the current state is detected to be in an unlimited power state, if the low-voltage side switch of the box-type transformer substation is switched off or a shutdown instruction is issued to the power generation unit in the previous control stage, the low-voltage side switch of the box-type transformer substation and the power generation unit are automatically recovered according to a load limiting execution degree priority strategy. According to the invention, by constructing a whole-process load-limiting control system from monitoring, warning, control to recovery, autonomous response and self-recovery of the photovoltaic power station under the condition of over-power generation are realized, and the automation and intelligence level of system operation is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automatic power generation control of grid-connected photovoltaic power stations, and in particular to a method for controlling emergency limited load of grid-connected photovoltaic power stations. BACKGROUND

[0002] A conventional automatic power generation control substation system (AGC substation for short) of a photovoltaic power station automatically adjusts active power output according to a real-time instruction issued by a dispatching master station of a power system and in accordance with a similar margin strategy of active power of a generator set in the whole field, and controls the active power of the photovoltaic power station in the whole field to be maintained within a set range at a certain rate. With the increasing capacity of photovoltaic power stations and the increasing number of photovoltaic power generation units, the network link and level of the equipment are increasingly complex. In an abnormal situation (such as network failure or photovoltaic power generation unit failure), the photovoltaic power generation unit is uncontrollable, and the actual value of the active power in the whole field may continuously exceed the target instruction issued by the dispatching master station, resulting in that the AGC substation cannot meet the requirements of the dispatching master station and affecting the safe and stable operation of the power grid.

[0003] For the situation that the active power in the whole field of photovoltaic power station continuously exceeds, the conventional processing methods are as follows: ①, monitoring the situation that the active power in the whole field of photovoltaic power station exceeds, only generating an overrunning alarm, and manually processing by the operation and maintenance personnel of the power station; ②, in addition to generating an overrunning alarm, the 35kV photovoltaic power collection line is generally automatically cut off. The conventional method for processing the situation that the active power in the whole field of photovoltaic power station continuously exceeds essentially needs the intervention of the operation and maintenance personnel of the photovoltaic power station, whether it is only an overrunning alarm or automatically cutting off the 35kV photovoltaic power collection line. The method of only overrunning alarm needs the high timeliness of the operation and maintenance personnel, and the operation and maintenance personnel need to manually intervene immediately when the overrunning alarm is generated. The method of automatically cutting off the 35kV photovoltaic power collection line needs the operation and maintenance personnel of the power station to take measures to restore the 35kV photovoltaic power collection line after solving the overrunning problem. In the actual operation process of the photovoltaic power station, the operation and maintenance personnel of the power station generally need to report to the dispatching center of the power system about the cutting off of the 35kV photovoltaic power collection line, and then apply for the restoration of the cut-off 35kV photovoltaic power collection line. In the reporting and applying process after automatically cutting off the 35kV photovoltaic power collection line, there is an unavoidable economic loss due to the time cost.

[0004] The method of only overrunning alarm is extremely dependent on the processing timeliness of the on-site operation and maintenance personnel, and cannot produce substantial effect in the case that the operation and maintenance personnel cannot handle it in time. The method of automatically cutting off the 35kV photovoltaic power collection line has single control means, the fault range is expanded, cannot achieve precise and flexible control, and also does not have a self-restoration function. In order to solve the above problems, it is urgent to develop a method for controlling emergency limited load of grid-connected photovoltaic power stations. SUMMARY

[0005] In view of the above problems, the present application 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 shedding execution degree when the power generation unit executes the active power reduction target instruction: For the i-th photovoltaic power generation unit, obtain the active power target instruction P of the j-th time iGoalj , as well as 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 ; Set the active power control accuracy of the i-th photovoltaic power generation unit to P iCon , and the active power control accuracy represents the minimum executable active power step of the power generation unit, which is set to 0.5% of the rated active power of the power generation unit; when holds, it indicates that the current is in the active power reduction target instruction cycle, then the execution degree of the j-th time ; Correct , when holds, set to 0, that is, when holds, , indicating that when the active power actual value rises after the power generation unit executes the active power reduction instruction, the load shedding execution degree of this time is corrected to 0; when holds, set to 1, that is, when holds, 1, indicating that when the active power actual value is lower than the target value after the power generation unit executes the active power reduction instruction, the load shedding execution degree of this time is corrected to 1, and then take the average value of the execution degrees multiple times to obtain the load shedding execution degree of the i-th photovoltaic power generation unit, where M is 5 times; the load shedding execution degree is closer to 0, indicating a lower execution degree when the power generation unit executes the active power reduction target instruction; the load shedding execution degree is closer to 1, indicating a higher execution degree when the power generation unit executes the active power reduction target instruction.

[0015] As a preferred solution of the emergency load shedding control method for the total active power over-generation of the grid-connected photovoltaic power station described in the present invention, wherein: Monitor the continuous over-generation duration of the total active power of the photovoltaic power station, and generate corresponding over-generation warning signals according to different over-generation durations, including:

[0016] The accumulation of the time scale of the total active power over-generation signal of the whole station generated during the monitoring stage. When the total active power over-generation signal TS of the whole station pbo is in the closed position, start timing, and use t pbo to represent the current continuous over-generation duration; Set four over-generation duration stages, namely T1, T2, T3, T4, and satisfy T1 < T2 < T3 < T4; when holds, generate the first-period continuous over-generation warning signal TS pboT1 ; when holds, generate the second-period continuous over-generation warning signal TSpboT2 ; when , a third time period continuous overrunning alarm signal TS pboT3 ; when , a fourth time period continuous overrunning alarm signal TS pboT4 ; when in any overrunning time period, the overrunning signal TS pbo is reset, i.e. the total active power of the whole station is restored to the normal state, then all the sub time period overrunning alarm signals are reset, i.e. TS pboT1 , TS pboT2 , TS pboT3 , TS pboT4 are all set to the sub position.

[0017] As a preferred scheme of the grid-connected photovoltaic power station whole station active overrunning emergency limited load control method described in the application, wherein: according to the current different overrunning alarm time period, corresponding emergency limited load strategy control is carried out, including:

[0018] When in the first overrunning time period, the active target value of all the power generation units is proportionally adjusted according to the current real-time active value; when the first time period continuous overrunning alarm signal TS pboT1 is detected to be in the normal position, the active actual value P iReal of all the power generation units is obtained, and the active target value of all the power generation units is calculated as P according to the set adjustment proportion coefficient a; when the continuous overrunning occurs, the real-time value of the current power generation unit is proportionally adjusted as a whole to reduce the active power of the whole station; after the active target value of the power generation unit is issued , if the first time period continuous overrunning alarm signal is still in the normal position after waiting for a certain adjustment time, the active target value of all the power generation units is proportionally adjusted again according to the real-time value, and the adjustment is repeated M times, while satisfying ;

[0019] In the second to fourth overrunning control stage, the limited load execution degree priority strategy is introduced as the adjustment basis; the power generation unit with high limited load execution degree is preferentially selected in the second overrunning time period, and the power generation unit with low limited load execution degree is preferentially selected in the third and fourth overrunning time periods.

[0020] As a preferred scheme of the grid-connected photovoltaic power station whole station active overrunning emergency limited load control method described in the application, wherein: according to the current different overrunning alarm time period, corresponding emergency limited load strategy control is carried out, further including:

[0021] When in the second overrunning time period, the active target value of zero is issued to the selected power generation unit according to the limited load execution degree priority strategy; when the second time period continuous overrunning alarm signal TS pboT2 is detected to be in the normal position, the active actual value P iRealAnd the load limit degree of execution ;

[0022] When X generating units are selected, if , the selection is stopped and zero active target values are issued to the selected X generating units; after a certain adjustment time, if the second period continuous overproduction alarm signal is still in the on state, the sorting is performed again according to the load limit degree of execution priority strategy, and the selection is performed from high to low, and it is ensured that the generating units selected in the last round of adjustment are not selected again, when Y generating units are selected, if , the selection is stopped and zero active target values are issued to the selected Y generating units; the process is repeated multiple times, and finally the actual controlled generating units reduce the active actual value to zero.

[0023] As a preferred scheme of the grid-connected photovoltaic power station full-station active overproduction emergency load limiting control method, according to the current different overproduction alarm periods, corresponding emergency load limiting strategy control is performed, and the method further includes: when in the third overproduction period, a shutdown instruction is issued to the selected generating units according to the load limit degree of execution priority strategy; when the third period continuous overproduction alarm signal TS pboT3 is detected to be in the on state, the active actual values P iReal of all generating units are acquired, and the load limit degree of execution is calculated. ;

[0024] When X generating units are selected, if , the selection is stopped and a shutdown instruction is issued to the selected X generating units; after a certain adjustment time, if the third period continuous overproduction alarm signal is still in the on state, the selection is performed again according to the load limit degree of execution priority strategy, and it is ensured that the generating units selected in the last round of adjustment are not selected again, when Y generating units are selected, if , the selection is stopped and a shutdown instruction is issued to the selected Y generating units; the process is repeated multiple times, and finally the corresponding number of generating units stop power generation.

[0025] As a preferred scheme of the grid-connected photovoltaic power station full-station active overproduction emergency load limiting control method, according to the current different overproduction alarm periods, corresponding emergency load limiting strategy control is performed, and the method further includes:

[0026] When in the fourth overproduction period, the low-voltage side switch of the selected generating unit corresponding to the box transformer is disconnected according to the load limit degree of execution priority strategy; when the fourth period continuous overproduction alarm signal TS pboT4 is detected to be in the on state, the active actual values P iReal of all generating units are acquired, and the load limit degree of execution is calculated. ;

[0027] When X generating units are selected, the following condition is met , the selection is stopped and the low-voltage side switch corresponding to the selected X generating units is given a disconnection instruction; after waiting for a certain adjustment time, if the fourth period continues to send the over-generation alarm signal and is still in the on state, the selection is performed again according to the priority strategy of the load limiting degree, and it is ensured that the generating units selected in the last round of adjustment are not selected again, when Y generating units are selected, the following condition is met , the selection is stopped and the low-voltage side switch corresponding to the selected Y generating units is given a disconnection instruction; the above process is repeated multiple times, and finally a corresponding number of generating units stop generating electricity;

[0028] In any over-generation period, when the total active power of the whole station returns to the normal state, that is, when the over-generation signal TS pbo is reset, it indicates that the current control strategy has achieved the effect of load limiting, and the control stage is exited; when the generating unit body control fails, the low-voltage side switch corresponding to the generating unit is controlled to achieve the forced shutdown of the generating unit.

[0029] As a preferred scheme of the emergency load limiting control method for the total active power over-generation of the grid-connected photovoltaic power station, when it is detected that the current is not in the load limiting state, if the low-voltage side switch of the transformer or the shutdown instruction of the generating unit is disconnected in the previous control stage, the low-voltage side switch of the transformer and the generating unit are automatically restored according to the priority strategy of the load limiting degree, including:

[0030] When it is detected that the current is not in the load limiting state, if the low-voltage side switch of the transformer or the shutdown instruction of the generating unit is disconnected in the previous control stage, the low-voltage side switch of the transformer and the generating unit are automatically restored according to the priority strategy of the load limiting degree; the actual value P bReal of the total active power of the photovoltaic power station and the target value P bGoal of the total active power of the photovoltaic power station sent by the dispatching are obtained, and the target active dead zone is set to P bDead ;

[0031] When , that is, when the actual value of the total active power of the photovoltaic station is within the range of the target value plus the target active dead zone, the total active power of the photovoltaic station is adjusted to the target value; the target active dead zone is set to 0.5% of the rated active power of the whole station, when and the duration exceeds T ul , it indicates that the total active power of the whole station is not in the load limiting state, and the restoration operation is performed at this time;

[0032] In the restoration operation, the generating unit whose corresponding low-voltage side switch of the transformer is in the on state but is in the shutdown state is preferentially restored; first, all generating units in the shutdown state and having the corresponding low-voltage side switch of the transformer in the on state are screened out, the rated active power P jN and the load limiting degree of the generating units are obtained, and the generating units are sorted according to the load limiting degree in descending order; 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.

[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] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following embodiments are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0039] Figure 1 Flow chart of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 2 Flow chart of the whole station active power overrunning state determination in the monitoring stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 3 Flow chart of the power generation unit limit load execution degree in the monitoring stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 4 Flow chart of the time period overrunning alarm in the alarm stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 5 Schematic diagram of the whole station active power overrunning signal and the first to fourth time period overrunning signals of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 6 Flow chart of the first time period overrunning control in the control stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 7 Flow chart of the second time period overrunning control in the control stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 8 Flow chart of the third time period overrunning control in the control stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 9 Flow chart of the fourth time period overrunning control in the control stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station; Figure 10 Flow chart of the recovery stage of the emergency limit load control method for the whole station active power overrunning of the grid-connected photovoltaic power station. DETAILED DESCRIPTION

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

[0041] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present application.

[0042] Second, the "one embodiment" or "an embodiment" referred to herein as including a particular feature, structure, or characteristic under discussion can include, where applicable, any particular feature, structure, or characteristic combined with any one or more other particular features, structures, or characteristics previously or subsequently discussed in any combination. Thus, appearances of the phrase "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0043] Embodiment 1

[0044] Reference Figures 1-10 For the first embodiment of the present application, the embodiment provides a kind of active emergency limit load control method of full station of grid-connected photovoltaic power station, comprising:

[0045] S1: real-time monitoring is carried out to the total active of photovoltaic power station full station and the active of all photovoltaic power generation units.

[0046] Further, the actual value P of the total active of photovoltaic power station full station is collected in real time bReal And the actual value P of the active of all power generation units iReal At the same time, the target value P of the total active of photovoltaic power station full station issued by dispatching bGoal And the target value P of the active allocated to all power generation units by AGC substation iGoal ; whether the total active of full station is continuously over-released: the over-release deviation value of the total active of photovoltaic power station full station is set as To prevent the shock caused by power fluctuation, the over-release recovery value is set as , and meet ; The over-release deviation value is set as 1% of the rated active of full station, and the over-release recovery value can be set as 0.8% of the rated active of full station; when , the total active over-release signal TS pbo is set to 1, indicating that the total active of full station enters the over-release state; when the total active over-release signal TS pbo is 1, and , the over-release signal TS pbo is reset to 0, indicating that the total active of full station restores to normal state;

[0047] The limit load execution degree when the power generation unit executes the active reduction target instruction is evaluated: for the i photovoltaic power generation unit, the j active target instruction P is obtained iGoalj , the actual value P of the active before executing the target instruction iRealj And the actual value P' of the active after executing the target instructioniRealj ; set the active control precision of the i-th photovoltaic power generation unit as P iCon The active control precision represents the minimum executable active step of the power generation unit, which is set as 0.5% of the rated active of the power generation unit; when , it indicates that the current is in the active reduction target instruction period, and the j-th execution degree of the limit load is ; is corrected, and when , the is corrected to 0, that is, when , the , indicates that the actual active value rises after the power generation unit executes the active reduction instruction, at this time, the limit load execution degree of the current time is corrected to 0; when , the is corrected to 1, that is, when , the , 1, indicates that the actual active value is lower than the target value after the power generation unit executes the active reduction instruction, at this time, the limit load execution degree of the current time is corrected to 1, and the execution degree is averaged for multiple times to obtain the limit load execution degree of the i-th photovoltaic power generation unit , wherein M is 5; the closer the limit load execution degree is to 0, the lower the execution degree of the power generation unit when executing the active reduction target instruction; the closer the limit load execution degree is to 1, the higher the execution degree of the power generation unit when executing the active reduction target instruction.

[0048] It should be noted that, as shown in the monitoring stage, it is judged whether the total active of the whole station is continuously overrated. First, the actual value and the target value of the total active of the whole station are obtained. It is judged whether the total active overrated signal of the whole station is in the on position: when the total active overrated signal of the whole station is in the on position, if the actual value of the total active of the whole station is greater than the target value of the total active of the whole station plus the overrated deviation value, the total overrated signal of the whole station is set to the on position; when the total active overrated signal of the whole station is in the on position, if the actual value of the total active of the whole station is less than the target value of the total active of the whole station plus the overrated return value, the total overrated signal of the whole station is set to the off position. Figure 2 As shown in the monitoring stage, the limit load execution degree of all power generation units is calculated. If there is a unit limit load execution degree that has not been calculated, a unit is selected, the active target value of the last adjustment period and the active actual value of the last adjustment period are obtained. If the active target value of the last adjustment period is less than the active actual value of the last adjustment period, the current actual value of the unit is obtained, and the execution degree of the last adjustment period is calculated according to the formula. The calculated execution degree is corrected, and the corrected execution degree is averaged for M times. The following illustrates the calculation process of the limit load execution degree of the power generation unit.

[0049] Figure 3

[0050] ​​​Suppose the rated active power of a power generation unit is 3 MW, and the control accuracy is set to 0.015 MW. In the first adjustment period, the actual active power of the power generation unit is 2.5 MW, and the target value issued is 2 MW. In the second adjustment period, the actual active power of the power generation unit is 2.2 MW, and the target value issued is continuously 2 MW, at which time the limit load execution degree is calculated . In the third adjustment period, the actual active power of the power generation unit is 2.05 MW, and the target value issued is 1.5 MW, at which time the limit load execution degree is calculated . In the fourth adjustment period, the actual active power of the power generation unit is 1.8 MW, and the target value issued is 1.5 MW, at which time the limit load execution degree is calculated 45. In the fifth adjustment period, the actual active power of the power generation unit is 1.6 MW, and the target value issued is 1.5 MW, at which time the limit load execution degree is calculated 66. In the sixth adjustment period, the actual active power of the power generation unit is 1.5 MW, and the target value issued is 1.5 MW, at which time the limit load execution degree is calculated 1. At this time, the average limit load execution degree H is calculated for 5 times.

[0051] Table 1 Limit load adjustment process and execution degree statistics table of power generation unit

[0052]

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

[0054] Further, the time scale accumulation of the total active power over-generation signal generated in the monitoring stage is accumulated, and when the total active power over-generation signal TS pbo is on, the timing starts, and t pbo represents the current duration of continuous over-generation; four over-generation duration stages are set, respectively T1, T2, T3, T4, and satisfy T1<T2<T3<T4; when , the first period continuous over-generation alarm signal TS pboT1 is generated; when , the second period continuous over-generation alarm signal TS pboT2 is generated; when , the third period continuous over-generation alarm signal TS pboT3 is generated; when , the fourth period continuous over-generation alarm signal TS pboT4 is generated; when the over-generation signal TS pbo is reset, that is, the total active power returns to the normal state, all sub-period over-generation alarm signals are reset, that is, TS pboT1 , TS pboT2 , TSpboT3 , TS pboT4 are set to the split position.

[0055] It should be noted that, as Figure 4 indicated, in the alarm phase, it is judged whether the total station active over-issuing signal is in the on position: when the total station over-issuing signal is in the on position, the duration of the current continuous over-issuing is calculated. If the continuous over-issuing duration is greater than the first period over-issuing duration, the first period over-issuing alarm signal is set to the on position. If the continuous over-issuing duration is greater than the second period over-issuing duration, the second period over-issuing alarm signal is set to the on position. If the continuous over-issuing duration is greater than the third period over-issuing duration, the third period over-issuing alarm signal is set to the on position. If the continuous over-issuing duration is greater than the fourth period over-issuing duration, the fourth period over-issuing alarm signal is set to the on position; when the total station over-issuing signal is in the split position, all period over-issuing alarm signals are set to the split position. The following illustrates the relationship between the total station active over-issuing signal and the first to fourth period over-issuing signals.

[0056] As Figure 5 indicated, in the alarm phase, it is assumed that T1=60 seconds, T2=180 seconds, T3=300 seconds, and T4=420 seconds. At the 00:00 second start time, the total station over-issuing signal is in the split position, at the 00:30 second time, the total station over-issuing signal is in the on position, and after 60 seconds of T1 cumulative determination time, at the 01:30 second time, the first period over-issuing alarm signal TS pboT1 is in the on position. When the total station over-issuing signal on position time lasts for 180 seconds to reach the T2 cumulative determination time, at the 03:30 second time, the second period over-issuing alarm signal TS pboT2 is in the on position. When the total station over-issuing signal on position time lasts for 300 seconds to reach the T3 cumulative determination time, at the 05:30 second time, the third period over-issuing alarm signal TS pboT3 is in the on position. When the total station over-issuing signal on position time lasts for 420 seconds to reach the T4 cumulative determination time, at the 07:30 second time, the fourth period over-issuing alarm signal TS pboT4 is in the on position. When the total station over-issuing signal resets at the 08:30 second time, the first to fourth period over-issuing signals all reset.

[0057] S3: According to the current different over-issuing alarm period, corresponding emergency load limiting strategy control is performed.

[0058] Further, when in the first over-issuing period, according to the current real-time active value, the active target value of all power generation units is proportionally adjusted downward; when it is detected that the first period continuous over-issuing alarm signal TS pboT1 is in the on position, the active actual value P iReal of all power generation units is obtained, and according to the set downward adjustment proportion coefficient a, the active target value of all power generation units is calculated as ; in the case of persistent over-release, the actual release value of the current power generation unit is used to proportionally reduce the overall active power of the station; the active target value is sent to the power generation unit After a certain adjustment time, if the first period persistent over-release alarm signal is still in the on state, the active target value of all power generation units is proportionally reduced again according to the actual release value, and the adjustment is repeated M times, while satisfying ;

[0059] In the second to fourth over-release control stages, the limit load execution degree priority strategy is introduced as the adjustment basis; in the second over-release period, the power generation unit with a high limit load execution degree is preferentially selected, and in the third and fourth over-release periods, the power generation unit with a low limit load execution degree is preferentially selected.

[0060] Further, when in the second over-release period, the active target value of zero is sent to the selected power generation unit according to the limit load execution degree priority strategy; when the second period persistent over-release alarm signal TS pboT2 is in the on state, the active actual value P iReal and the limit load execution degree of all power generation units are obtained.

[0061] When X power generation units are selected, if , the selection is stopped, and the active target value of zero is sent to the selected X power generation units; after a certain adjustment time, if the second period persistent over-release alarm signal is still in the on state, the sorting is performed again according to the limit load execution degree priority strategy, and the power generation units selected in the last round of adjustment are not selected again, when Y power generation units are selected, if , the selection is stopped, and the active target value of zero is sent to the selected Y power generation units; the process is repeated multiple times, and finally the actual controlled power generation units reduce the active actual value to zero.

[0062] Further, when in the third over-release period, the shutdown instruction is sent to the selected power generation unit according to the limit load execution degree priority strategy; when the third period persistent over-release alarm signal TS pboT3 is in the on state, the active actual value P iReal and the limit load execution degree of all power generation units are obtained.

[0063] When X power generation units are selected, if , the selection is stopped, and the shutdown instruction is sent to the selected X power generation units; after a certain adjustment time, if the third period persistent over-release alarm signal is still in the on state, the selection is performed again according to the limit load execution degree priority strategy, and the power generation units selected in the last round of adjustment are not selected again, when Y power generation units are selected, if 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, 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 that the current total active power of the whole station is 20 MW, the active power target value of the whole station is 10 MW, the over-issuing deviation value is set to 1 MW, and the over-issuing return value is set to 0.8 MW. Assume that there are 5 generating units, and the current actual value of each generating unit is 4 MW. The limiting load execution degrees of the generating units are sorted in descending order as 0.95, 0.80, 0.70, 0.50, and 0.40. In the first adjustment, the three generating units with limiting load execution degrees of 0.95, 0.80, and 0.70 are selected, that is, the selected generating units satisfy the determination condition 4+4+4>20-(10+0.8), and the active power target values of 0 of the selected generating units are issued. In the second adjustment, the active power actual values of the generating units with limiting load execution degrees of 0.95 and 0.80 are 0, but the active power actual value of the generating unit with limiting load execution degree of 0.7 is still 4 MW. At this time, the total active power of the whole station is 12 MW, and the over-issuing state continues to be adjusted. The currently selected generating units are no longer selected, and the generating unit with limiting load execution degree of 0.5 is selected, that is, 4>12-(10+0.8), and the active power target values of 0 of the selected generating units are issued. In the third adjustment, the active power actual value of the generating unit with limiting load execution degree of 0.5 is 0, at this time, the total active power of the whole station is 8 MW, and the over-issuing state no longer exists, and the limiting load adjustment is ended. As shown in Table 3, the limiting load execution degrees of the generating units and the active power responses in the adjustment are shown in the following table 3.

[0073]

[0074] As Figure 8As shown, in the control phase, if the first, second, third and fourth period over-issuing alarm signal is high, the third period over-issuing limit load control strategy is adopted. The current real-time active power of all generating units is obtained, and if the maximum adjustment times is not reached, the limit load execution degree priority strategy is adopted, and the generating units are sorted according to the limit load execution degree from low to high. A generating unit is selected, and the real-time active power values of all selected generating units are added. When the real-time active power value of all selected generating units is greater than the total active power actual value of the station minus the total active power target value of the station plus the active power over-issuing recovery value, the selection of the generating unit is stopped, and the shutdown instruction is issued to all selected generating units, otherwise the selection of the generating unit is continued. In the third and fourth period over-issuing control, the generating unit limit load execution degree is sorted from low to high, and the generating unit with low limit load execution degree is preferentially selected for shutdown, which is different from the second period over-issuing control, in which the generating unit limit load execution degree is sorted from high to low, and the generating unit with high limit load execution degree is preferentially selected. In the second period over-issuing control, the generating unit needs to execute the zero value of the active power target value, and at this time, the generating unit with higher controlled degree is more conducive to actively reducing the active power value to zero. In the third and fourth period over-issuing control, the generating unit is stopped through different means, at this time, the generating unit with low controlled degree is selected to avoid wasting the execution opportunity of the controllable generating unit, and is conducive to the subsequent recovery process. The third period over-issuing control process is illustrated below.

[0075] It is assumed that the total active power of the station is 20 MW, the active power target value of the station is 10 MW, the over-issuing deviation value is set to 1 MW, and the over-issuing recovery value is set to 0.8 MW. It is assumed that there are five generating units, and the current actual value of each generating unit is 4 MW, and the generating unit limit load execution degree is sorted from small to large as 0.2, 0.4, 0.6, 0.8 and 0.9. During the first adjustment, three generating units with limit load execution degrees of 0.2, 0.4 and 0.6 are selected, that is, the judgment condition 4+4+4>20-(10+0.8) is met, and the shutdown remote control instruction is issued to the selected generating units. During the second adjustment, the generating units with limit load execution degrees of 0.2 and 0.4 may have been shut down, but the active power actual value of the generating unit with limit load execution degree of 0.6 is still 4 MW, at this time, the total active power of the station is 12 MW, and the adjustment is continued in the over-issuing state. The selected generating units are not selected again, and the generating unit with limit load execution degree of 0.8 is selected, that is, 4>12-(10+0.8) is met, and the shutdown remote control instruction is issued to the selected generating units. During the third adjustment, the generating unit with limit load execution degree of 0.8 has been shut down, at this time, the total active power of the station is 8 MW, and the over-issuing state is not reached, and the limit load adjustment is ended, as shown in the following table 4.

[0076] Table 4 Hierarchical shutdown adjustment process based on limit load execution degree and active power response table

[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, and 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] Assume that after completing the load limiting control, the station total active power is 10 MW, and the station active power target value is 25 MW. Assume that the maximum number of start-ups is 2, and the start-up waiting time is 2 minutes. Assume that 5 generating units are in a shutdown state, of which 3 generating units are shutdown but the corresponding box transformer low-voltage side switch is in the closed position, and 2 generating units are in the corresponding box transformer low-voltage side switch is in the open position. Assume that the rated active power of the 5 generating units is 4 MW. The load limiting execution degrees of the 3 shutdown generating units are 0.9, 0.8, and 0.6 from high to low, and the load limiting execution degrees of the 2 box transformer low-voltage side switch open position generating units are 0.4 and 0.2 from high to low. In the first adjustment, the shutdown generating units with the box transformer low-voltage side switch in the closed position are preferentially selected, and the maximum number of start-ups and the difference between the actual value and the target value are comprehensively judged to select two generating units with load limiting execution degrees of 0.9 and 0.8 to issue start-up instructions. After 2 minutes of start-up waiting time, assume that the two generating units are successfully started and accept the new target value, and the actual active power of each is 2 MW, at this time the station total active power is 14 MW, and it is judged that it is still in the unlimited power state. At this time, the shutdown generating units with the box transformer low-voltage side switch in the closed position are preferentially selected, and the generating unit with a load limiting execution degree of 0.6 is issued a start-up instruction. After 2 minutes of start-up waiting time, assume that the second adjustment generating unit is successfully started and accepts the new target instruction, and the actual active power is 2 MW, at this time the station total active power is 16 MW, and it is judged that it is still in the unlimited power state. At this time, the generating units with the box transformer low-voltage side switch in the open position are selected, and the generating units with load limiting execution degrees of 0.4 and 0.2 are selected to issue closed position instructions to the corresponding box transformer low-voltage side switches. After 2 minutes of start-up waiting time, assume that the third adjustment generating unit box transformer low-voltage side switch closed position is successful, at this time the station total active power is 16 MW, and it is judged that it is still in the unlimited power state, at this time the generating units with load limiting execution degrees of 0.4 and 0.2 are selected to issue start-up instructions. After 2 minutes of start-up waiting time, assume that the fourth adjustment generating unit is successfully started, at this time all generating units return to normal, and the recovery logic is exited, as shown in the following Table 5:

[0087] Table 5 Generating unit recovery adjustment process and station active power change table in the load limiting release stage

[0088]

[0089] The embodiment also provides a computer device suitable for the grid-connected photovoltaic power station station active power over-release emergency load limiting control method, 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 grid-connected photovoltaic power station station active power over-release emergency load limiting control method proposed in the above embodiment.

[0090] The computer device can be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected by a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is configured to perform wired or wireless communication with an external terminal. The wireless communication can be achieved by WIFI, an operator network, NFC (Near Field Communication) or other technologies. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, trackball or touchpad arranged on the shell of the computer device, or an external keyboard, touchpad or mouse, etc.

[0091] The embodiment also provides a storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the grid-connected photovoltaic power station full-station active power over-release emergency limited load control method 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 application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and all of them should be covered in the scope of the claims of the present application.

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 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.

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 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, 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.

3. 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: The accumulation of the time scale of the total active power over - generation signal for the whole station during the monitoring stage. When the total active power over - generation signal TS of the whole station pbo is in the closed position, start timing and use t pbo to represent the current continuous over - generation duration; set four over - generation duration stages, namely T1, T2, T3, T4, and satisfy T1 < T2 < T3 < T4; when occurs, generate the first - period continuous over - generation alarm signal TS pboT1 ; when occurs, generate the second - period continuous over - generation alarm signal TS pboT2 ; when occurs, generate the third - period continuous over - generation alarm signal TS pboT3 ; when occurs, generate the fourth - period continuous over - generation alarm signal TS pboT4 ; when within 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, then all the sub - period over - generation alarm signals are reset, that is, TS pboT1 , TS pboT2 / / , TS pboT3 , TS pboT4 are all set to the off position.

4. The emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in claim 1, 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.

5. The emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in claim 1 or 4, 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.

6. The emergency load limiting control method for active power over-generation of a grid-connected photovoltaic power station as described in claim 1 or 4, characterized in that: The method of implementing corresponding emergency load limiting strategy control based on different over-generation alarm periods also includes: when in the third over-generation period, issuing a shutdown command to the selected power generation unit according to the load limiting execution priority strategy; detecting the third period continuous over-generation alarm signal TS. 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.

7. The emergency load limiting control method for active power overload of a grid-connected photovoltaic power station as described in claim 1 or 4, 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.

8. The emergency load limiting control method for active power over-generation of 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.

9. 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 8.

10. 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 8.

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