Method for cooperatively controlling active power by two types of inverters during limited power period of photovoltaic power station

Abstract

The invention relates to a method for cooperatively controlling active power by two inverters in a limited power period of a photovoltaic power station, which comprises the following steps of: acquiring a power grid dispatching active power target in real time, judging the total capacity of the power grid dispatching active power target and a sample inverter, and performing corresponding operation according to a judgment result; the method relates to AGC related control quitting of a sample plate inverter, pre-control of cooperative control of the sample plate inverter and a non-sample plate inverter, pre-control of independent sample plate inverter control, AGC control under a cooperative mode of the sample plate inverter and the non-sample plate inverter, and AGC control with independent participation of the sample plate inverter. According to the method, the shutdown inverter is reasonably judged and selected, when the target value of the active power is close to a certain range of the actual total active power value of the sample inverter, the sample inverter and the non-sample inverter cooperatively control the active power, frequent start and stop of the non-sample inverter are avoided, and the reliability of the inverter is improved. The active power control quality and the inverter operation quality are improved, and the service life of the inverter is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation control technology, and in particular to a method for coordinated control of active power of two types of inverters during the limited power period of a photovoltaic power station. Background Art

[0002] The "Calculation Method of Photovoltaic Theoretical Power Generation and Blocked Power" formulated by the State Grid requires using a reference inverter to calculate the photovoltaic theoretical power generation and blocked power of a photovoltaic power station. Therefore, the inverters of a photovoltaic power station are usually divided into two types: reference inverters and non-reference inverters. The reference inverter is often the selected representative inverter, and its photovoltaic theoretical power generation and blocked power of the photovoltaic power station are calculated by using it. It usually generates electricity freely without power generation control.

[0003] In fact, when the power grid urgently needs to reduce the active power, the dispatching will limit the active power of the photovoltaic power station. In this case, when the active power target value of the dispatching is lower than the available output power of the reference inverter, the photovoltaic power station usually takes the following measures: (1) manually control the output power of the reference inverter to reduce it; (2) put the reference inverter into AGC control (automatic generation control) to reduce the output power of the reference inverter through automatic control.

[0004] Currently, due to timely control, the method of putting the reference inverter into AGC control is adopted by more and more photovoltaic power stations to reduce the output power of the reference inverter. In order to take into account the representativeness of the reference inverter, when the reference inverter of the photovoltaic power station is put into the AGC mode, it usually controls the reference inverter to operate in the maximum active power output mode. Only when all non-reference inverters have stopped and the actual total active power output of the reference inverter in the maximum active power output mode is still higher than the active power target value will the output power of the reference inverter be controlled and limited. In practice, the following defects will occur in this method: when the difference between the active power target value and the actual total active power output value of the reference inverter is not too large, since the actual active power output of the reference inverter fluctuates at any time, that is, it is possible that the actual total active power output value of the reference inverter is greater than the active power target value at the previous moment and the output power of the reference inverter needs to be limited, but at the next moment, the actual total active power output value of the reference inverter is less than the active power target value, then it is necessary to supplement the output power of other non-reference inverters. However, when it is necessary to supplement the output power of other non-reference inverters, it is necessary to restart some of the non-reference inverters that have all stopped, so that the non-reference inverters will be restarted frequently, affecting the power control quality and the operation quality and life of the inverters. Summary of the Invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the situation in the prior art where when the power grid urgently needs to reduce the active power and limit the power output of the photovoltaic power station, the difference between the active power and the total actual active power of the sample inverter is small, resulting in the frequent start and stop of non-sample inverters, causing the decline of power control quality and inverter operation quality, and the reduction of the inverter operation life.

[0006] To solve the above technical problem, the present invention provides a method for collaborative control of active power of two types of inverters during the power limit period of a photovoltaic power station, including:

[0007] S1: Set the collaborative control function switch;

[0008] S2: Determine whether the collaborative control switch is turned on; if the collaborative control switch is in the on state, enter S3; if the collaborative control function switch is in the off state, return to S2;

[0009] S3: Obtain the characteristic information of the inverters in the photovoltaic power station, divide the inverters into non-sample inverters and sample inverters; control the initial state of the sample inverters to be not in the AGC state, control the initial state of the non-sample inverters to be in the AGC state, and establish an on-stack and an off-stack, where the initial values of the elements are all assigned as empty;

[0010] S4: Real-time collect the grid dispatching active power target value P target , determine the magnitude relationship between the grid dispatching active power target value and the total capacity of the sample inverters. If the grid dispatching active power target value is greater than or equal to the total capacity of the sample inverters, enter S5; if the grid dispatching active power target value is less than the total capacity of the sample inverters, enter step S6;

[0011] S5: Determine whether the sample inverters have been put into AGC, perform relevant control for the sample inverters to exit AGC, control the sample inverters to exit AGC, and keep the sample inverters running in the maximum power mode. After waiting for the completion of this control, return to S4;

[0012] S6: Select a non-sample inverter for collaborative regulation and a sample inverter for collaborative regulation; calculate the total actual active power value of all the sample inverters except the sample inverter for collaborative regulation, denoted as P1; calculate the difference between the sum of the available active power of the non-sample inverter for collaborative regulation and the total available active power of all the sample inverters and the correction margin value, denoted as P2; determine whether the condition of P1 < P target < P2 is satisfied. If it is satisfied, it is determined that the sample inverters and non-sample inverters need to collaborate to control the active power, and enter S7; if it is not satisfied, it is determined that the sample inverters and non-sample inverters do not need to collaborate to control the active power, and then determine the relationship between P target and P1, P2. If P target≤ P1, then enter S8. If P target ≥ P2, then return to S5;

[0013] S7: Perform pre-control for coordinated control of the sample inverter and non-sample inverters, and wait to enter S9 after this control is executed;

[0014] S8: Perform pre-control for the independent sample inverter, and wait to enter S10 after this control is executed;

[0015] S9: Perform AGC control in the coordinated mode of the sample inverter and non-sample inverters, and wait to return to S4 after this operation is executed;

[0016] S10: Perform AGC control with the independent participation of the sample inverter, and wait to return to S4 after this control is executed.

[0017] In an embodiment of the present invention, the establishment of the startup stack and the shutdown stack includes:

[0018] Establish a startup stack for storing the sample inverter elements and one non-sample inverter element during the startup process of the sample inverter participating in AGC control. Among them, the initial value of the startup stack element is assigned as empty; the one non-sample inverter element is the non-sample inverter with the smallest active power lower limit value among the non-sample inverters. Among them, the active power lower limit value is an inherent characteristic of the inverter, that is, the minimum active power for the inverter to maintain normal operation, which is a set fixed value;

[0019] Establish a shutdown stack for storing the sample inverter elements during the shutdown process of the sample inverter participating in AGC control. Among them, the initial value of the shutdown stack element is assigned as empty.

[0020] In an embodiment of the present invention, S5 includes:

[0021] Judge whether the sample inverter has been put into AGC. If the sample inverter has not been put into AGC, maintain the maximum power mode operation of the sample inverter, and the non-sample inverters participate in AGC to adjust the active power; if the sample inverter has been put into AGC, control the sample inverter to withdraw from AGC. When the shutdown stack is not empty, start all the sample inverters in the shutdown stack and control them to operate in the maximum power mode, clear the startup stack and the shutdown stack, and control the non-sample inverters to participate in AGC to adjust the active power.

[0022] In an embodiment of the present invention, S6 includes:

[0023] Select a non-template inverter with the smallest active power lower limit among the non-template inverters as the non-template inverter for coordinated regulation; select a template inverter with the largest active power lower limit among the template inverters as the template inverter for coordinated regulation. Here, the active power lower limit of each inverter is an inherent characteristic of each inverter, that is, the minimum active power for the inverter to maintain normal operation, which is a set fixed value;

[0024] Calculate P1 = the total actual active power value of all the other template inverters except the template inverter for coordinated regulation; calculate P2 = the available active power of the non-template inverter for coordinated regulation + the total available active power of all the template inverters - the correction margin value. Among them, the available active power can be calculated according to the light intensity and temperature of the photovoltaic power station, and the correction margin value is a set fixed value;

[0025] Judge whether the condition of P1 < P target < P2 is satisfied. If it is satisfied, it is determined that the template inverter and the non-template inverter need to coordinate and control the active power, and enter S7 to perform the pre-control of the coordinated control of the template inverter and the non-template inverter; if it is not satisfied, it is determined that the template inverter and the non-template inverter do not need to coordinate and control the active power, and then judge P target The relationship with P1 and P2. If P target ≤ P1, enter S8 to perform the pre-control of the independent template inverter control; if P target ≥ P2, return to S5 to perform the relevant control for the template inverter to exit AGC.

[0026] In an embodiment of the present invention, the pre-control of the coordinated control of the template inverter and the non-template inverter includes:

[0027] Judge whether the template inverter has been put into AGC control. If the template inverter has not been put into AGC control, push all the template inverter elements into the top of the startup stack in ascending order according to the active power lower limit of the template inverter, put all the template inverters into AGC control, and push the non-template inverter element for coordinated regulation into the top of the startup stack; if the template inverter has been put into AGC control, judge whether the shutdown stack is empty;

[0028] If the shutdown stack is not empty, pop the template inverter elements from the top of the shutdown stack in turn and push them into the top of the startup stack. For each popped template inverter element, start the template inverter until the shutdown stack is empty, and finally push the non-template inverter element for coordinated regulation into the top of the startup stack; if the shutdown stack is empty, when the inverter element at the top of the startup stack is not the non-template inverter element for regulation function, push the non-template inverter element for coordinated regulation into the top of the startup stack.

[0029] In one embodiment of the present invention, the pre-control of the independent template inverter control includes:

[0030] Judge whether the template inverter has been put into AGC control. If the template inverter has not been put into AGC control, push all the corresponding elements of the template inverters to the top of the startup stack in ascending order of the active power lower limit value of the template inverters, and put all the template inverters into AGC control; if the template inverter has been put into AGC control, when the element at the top of the startup stack is a non-template inverter element for coordinated regulation function, pop the element at the top of the startup stack.

[0031] In one embodiment of the present invention, the AGC control in the coordinated manner of the template inverter and the non-template inverter includes:

[0032] S91: When the non-template inverter for coordinated regulation function stops, control to start the non-template inverter for coordinated regulation function;

[0033] S92: Stop all non-template inverters that are not stopped except the non-template inverter for coordinated regulation function;

[0034] S93: Perform AGC control on all inverters in the startup stack in a coordinated manner. The specific steps are as follows: For the inverters corresponding to the first element and the second element at the top of the startup stack, perform equal-margin active power distribution and control, that is, perform equal-margin active power distribution and control on the non-template inverter for coordinated regulation function and the template inverter for coordinated regulation function; control the inverters corresponding to the remaining elements in the startup stack except the first element and the second element at the top of the stack, that is, control all the remaining template inverters except the template inverters corresponding to the non-template inverter element for coordinated regulation function, and control the remaining all template inverters to generate electricity in the maximum power mode.

[0035] In one embodiment of the present invention, the AGC control in which the template inverter participates independently includes:

[0036] S101: Stop all started non-template inverters;

[0037] S102: Control the startup and shutdown of the template inverter. The specific steps are as follows: Judge the grid dispatching active power target value P target and the current total active power lower limit value P currentmin . Among them, the current total active power lower limit value is the sum of the active power lower limit values of the template inverters corresponding to all elements in the current startup stack; if P target ≤P currentmin , then control to stop a specific template inverter, and wait to enter S103 after this control is completed; if P target >P currentmin , then judge the grid dispatching power target value Ptarget and the current total active power lower limit value P currentmin and the active power lower limit value P of the first pre-start unit prestartmin The sum, where P prestartmin is the active power lower limit value of the template inverter corresponding to the top element of the current shutdown stack;

[0038] When P target > P currentmin + P prestartmin then control to start a specific template inverter. After waiting for the execution of this control to be completed, enter S103; when P target ≤ P currentmin + P prestartmin then do not start any template inverters and enter S103;

[0039] S103: Perform equal margin active power distribution on all template inverters in the startup stack and perform active power regulation control. After waiting for the execution of this control to be completed, return to S4.

[0040] In an embodiment of the present invention, the control to stop a specific template inverter includes:

[0041] When P target ≤ P currentmin then update the startup stack and the shutdown stack, and stop a template inverter, recalculate P currentmin， and determine whether it still satisfies P target ≤ P currentmin ; if P target ≤ P currentmin then continue to update the startup stack and the shutdown stack, and stop a template inverter, continue to recalculate P currentmin and determine whether it still satisfies P target ≤ P currentmin until P target > P currentmin or the startup stack is empty;

[0042] Among them, the operation of updating the startup stack and the shutdown stack and stopping a template inverter is specifically: pop a template inverter element at the top of the startup stack, and push the popped template inverter element onto the top of the shutdown stack, and stop the template inverter corresponding to the element newly pushed onto the top of the shutdown stack;

[0043] The operation of recalculating P currentmin and determining whether it still satisfies P target ≤ P currentmin is specifically: recalculate the sum P of the active power lower limit values of all template inverters corresponding to all elements in the updated current startup stack currentmin and then re-determine whether it satisfies Ptarget ≤P currentmin condition.

[0044] In one embodiment of the present invention, the control to start a specific template inverter includes:

[0045] When P target > P currentmin + P prestartmin update the startup stack and the shutdown stack and start a template inverter, recalculate P currentmin and P prestartmin , and determine whether it still satisfies P target > P currentmin + P prestartmin ; if P target > P currentmin + P prestartmin , then continue to update the startup stack and the shutdown stack, and start a template inverter, continue to recalculate P currentmin and P prestartmin , and determine whether it still satisfies P target > P currentmin + P prestartmin , until P taget ≤P currentmin + P prestartmin or the shutdown stack is empty;

[0046] Among them, the operation of updating the startup stack and the shutdown stack and starting a template inverter is specifically: pop an element of a template inverter at the top of the shutdown stack, and push the popped element of the template inverter onto the top of the startup stack, and start the template inverter corresponding to the element newly pushed onto the top of the startup stack;

[0047] The operation of continuing to recalculate P currentmin and P prestartmin , and determine whether it still satisfies P target > P currentmin + P prestartmin is specifically: recalculate the sum of the lower active power limits of all template inverters corresponding to all elements in the current startup stack after update P currentmin and the lower active power limit P prestartmin of the template inverter corresponding to the top element of the current shutdown stack, and then determine whether it satisfies P target > P currentmin + P prestartmin condition.

[0048] The above technical solution of the present invention has the following advantages compared with the prior art:

[0049] (1) During the period when the power grid restricts the power of the photovoltaic power station, especially in a special power interval section, by adopting coordinated control of the active power by the sample inverter and the non-sample inverter, the situation where the non-sample inverter will frequently restart when only the sample inverter participates in AGC is avoided. At the same time, the power control quality and the inverter quality are improved, and the service life of the inverter is increased;

[0050] (2) The method of "AGC control under the coordinated mode of the sample inverter and the non-sample inverter" adopted by the present invention is beneficial to meeting the requirements of the power grid dispatching for active power first under the condition of severe power restriction, and at the same time can give full play to the sample role of some sample inverters;

[0051] (3) The method of "the sample inverter independently participates in AGC control" adopted by the present invention makes full use of the advantage of last-in, first-out of the stack, and sets up the start-up stack and the shutdown stack according to the active power lower limit. By reasonably exchanging elements between the start-up stack and the shutdown stack, during the period when the sample inverter participates in AGC control, especially when the target power is low, the requirements of the target power can still be met to the greatest extent, ensuring that the sample inverter can operate normally above the active power lower limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to make the content of the present invention easier to be clearly understood, the following further describes the present invention in detail according to the specific embodiments of the present invention in combination with the drawings, where

[0053] Figure 1 is a flowchart of a method for coordinated control of active power by two types of inverters during the power limit period of a photovoltaic power station provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] The following further describes the present invention in combination with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and can implement it, but the embodiments cited do not limit the present invention.

[0055] Embodiment 1

[0056] Referring to Figure 1 As shown, a method for coordinated control of active power by two types of inverters during the power limit period of a photovoltaic power station of the present invention has the following specific operation steps:

[0057] S1: Set the coordinated control function switch;

[0058] S2: Determine whether the coordinated control switch is turned on; if the coordinated control switch is in the on state, enter S3; if the coordinated control function switch is in the off state, return to S2;

[0059] S3: Obtain the characteristic information of the inverters in the PV power station, and classify the inverters into non-sample inverters and sample inverters; control the initial states of the inverters, that is, control the initial state of the sample inverters to be not put into the AGC state, and control the initial state of the non-sample inverters to be put into the AGC;

[0060] Establish a start-up stack for storing the sample inverter elements and one non-sample inverter element that are powered on during the AGC control process of the sample inverters. Among them, the initial value of the start-up stack element is assigned as empty; one non-sample inverter element is the non-sample inverter with the smallest active power lower limit value among the non-sample inverters; among them, the active power lower limit value is an inherent characteristic of the inverter, that is, the minimum active power for the inverter to maintain normal operation, and it is a set fixed value;

[0061] Establish a shutdown stack for storing the sample inverter elements that are shut down during the AGC control process of the sample inverters. Among them, the initial value of the shutdown stack element is assigned as empty;

[0062] The said elements, whose scope includes sample inverter elements and one selected non-sample inverter element for coordinated regulation function;

[0063] S4: Real-time collect the grid dispatching active power target value P target , judge the magnitude relationship between the grid dispatching active power target value and the total capacity of the sample inverters. If the grid dispatching active power target value is greater than or equal to the total capacity of the sample inverters, enter S5; if the grid dispatching active power target value is less than the total capacity of the sample inverters, enter step S6;

[0064] S5: Judge whether the sample inverters have been put into the AGC. If the sample inverters have not been put into the AGC, keep the sample inverters running in the maximum power mode, and the non-sample inverters participate in the AGC to regulate the active power; if the sample inverters have been put into the AGC, control the sample inverters to exit the AGC. When the shutdown stack is not empty, start all the sample inverters in the shutdown stack and control them to run in the maximum power mode, empty the start-up stack and the shutdown stack, and control the non-sample inverters to participate in the AGC to regulate the active power;

[0065] After waiting for the completion of the execution of this control, return to S4;

[0066] S6: Select one non-sample inverter with the smallest active power lower limit value among the non-sample inverters as the non-sample inverter for coordinated regulation function; select one sample inverter with the largest active power lower limit value among the sample inverters as the sample inverter for coordinated regulation function. Among them, the active power lower limit value of each inverter is an inherent characteristic of each inverter, that is, the minimum active power for the inverter to maintain normal operation, and it is a set fixed value;

[0067] Calculate the actual total active power value of all sample inverters except the sample inverter with coordinated regulation function, denoted as P1, i.e., P1 = the actual total active power value of all sample inverters except the sample inverter with coordinated regulation function; calculate the difference between the sum of the available active power of the non-sample inverter with coordinated regulation function and the total available active power of all sample inverters and the correction margin value, denoted as P2, i.e., P2 = the available active power of the non-sample inverter with coordinated regulation function + the total available active power of all sample inverters - the correction margin value; where the available active power can be calculated based on the light intensity and temperature of the photovoltaic power station, and the correction margin value is a set fixed value.

[0068] Judge whether the condition P1 < P target < P2 is satisfied. If it is satisfied, it is determined that the sample inverter and the non-sample inverter need to jointly control the active power, enter S7, and perform the pre-control of the joint control of the sample inverter and the non-sample inverter; if it is not satisfied, it is determined that the sample inverter and the non-sample inverter do not need to jointly control the active power, and then judge P target The relationship with P1 and P2. If P target ≤ P1, enter S8 and perform the pre-control of the independent sample inverter control; if P target ≥ P2, return to S5 and perform the relevant control for the sample inverter to exit AGC.

[0069] S7: Judge whether the sample inverter has been put into AGC control. If the sample inverter has not been put into AGC control, push all sample inverter elements onto the top of the start stack in ascending order according to the lower limit of the active power of the sample inverter, put all sample inverters into AGC control, and push the non-sample inverter element with coordinated regulation function onto the top of the start stack; if the sample inverter has been put into AGC control, judge whether the stop stack is empty;

[0070] If the stop stack is not empty, pop the sample inverter elements from the stop stack one by one from the top and push them onto the top of the start stack. For each popped sample inverter element, start the sample inverter until the stop stack is empty, and finally push the non-sample inverter element with coordinated regulation function onto the top of the start stack; if the stop stack is empty, when the inverter element at the top of the start stack is not the non-sample inverter element with regulation function, push the non-sample inverter element with coordinated regulation function onto the top of the start stack;

[0071] Wait until the execution of this control is completed and then enter S9;

[0072] S8: Perform pre-control for independent template inverter control, and determine whether the template inverter has been put into AGC control. If the template inverter has not been put into AGC control, push all the elements corresponding to the template inverters onto the top of the startup stack in ascending order of the active power lower limit value of the template inverters, and put all the template inverters into AGC control. If the template inverter has been put into AGC control, determine whether the element at the top of the startup stack is an element of a non-template inverter for coordinated regulation function.

[0073] If the element at the top of the startup stack is an element of a non-template inverter for coordinated regulation function, pop the element at the top of the startup stack. If the element at the top of the startup stack is not an element of a non-template inverter for coordinated regulation function, do nothing.

[0074] Wait until the execution of this control is completed and then enter S10.

[0075] S9: Perform AGC control in the coordinated mode of the template inverter and non-template inverters. The specific operation steps are as follows:

[0076] S91: Determine whether the non-template inverter for coordinated regulation function is stopped. If the non-template inverter for coordinated regulation function is stopped, control to start the non-template inverter for coordinated regulation function. If the non-template inverter for coordinated regulation function is not stopped, do nothing.

[0077] S92: Stop all non-template inverters that are not stopped except the non-template inverter for coordinated regulation function.

[0078] S93: Perform AGC control in the coordinated mode for all inverters in the startup stack. The specific steps are as follows: For the inverters corresponding to the first and second elements at the top of the startup stack, perform equal-margin active power distribution and control, that is, perform equal-margin active power distribution and control for the non-template inverter for coordinated regulation function and the template inverter for coordinated regulation function. Control the inverters corresponding to the remaining elements except the first and second elements at the top of the startup stack, that is, control all the template inverters except the template inverters corresponding to the elements of the template inverter for coordinated regulation function, and control the above-mentioned all the template inverters to generate electricity in the maximum power mode.

[0079] Wait until the execution of this operation is completed and then return to S4.

[0080] S10: Perform AGC control with the independent participation of the template inverter, including:

[0081] S101: Stop all started non-template inverters.

[0082] S102: Control the startup and shutdown of the template inverter. The specific steps are as follows: Determine the active power target value P of the grid dispatching targetWith the current total active power lower limit value P currentmin wherein the current total active power lower limit value is the sum of the active power lower limit values of the sample inverters corresponding to all elements of the current startup stack;

[0083] (1) If P target ≤P currentmin , then perform the operation of controlling to stop a specific sample inverter: when P target ≤P currentmin , update the startup stack and the shutdown stack, and stop one sample inverter, recalculate P currentmin , and determine whether it still satisfies P target ≤P currentmin ; if P taget ≤P currentmin , continue to update the startup stack and the shutdown stack, and stop one sample inverter, continue to recalculate P currentmin and determine whether it still satisfies P target ≤P currentmin , until P target >P currentmin or the startup stack is empty;

[0084] Among them, the operation of updating the startup stack and the shutdown stack and stopping one sample inverter is specifically: pop a sample inverter element at the top of the startup stack, and push the popped sample inverter element onto the top of the shutdown stack, and stop the sample inverter corresponding to the element newly pushed onto the top of the shutdown stack;

[0085] The operation of recalculating P currentmin and determining whether it still satisfies P target ≤P currentmin is specifically: recalculate the sum P currentmin of the active power lower limit values of all sample inverters corresponding to all elements of the updated current startup stack, and then re-determine whether it satisfies the condition of P target ≤P currentmin ;

[0086] Due to the principle of last-in, first-out of the stack, the elements in the startup stack are pushed onto the stack in ascending order of the active power lower limit value of the sample inverter. When popping, it just makes the elements pop out of the stack in descending order of the active power lower limit value of the sample inverter. Pushing to the shutdown stack also just makes the elements enter the stack in descending order of the active power lower limit value of the sample inverter. This ensures that the shutdown order of the sample inverters is in descending order of the active power lower limit value of the sample inverter, and the sample inverter with a larger active power lower limit value is stopped first; it can make the sample inverters operate normally above the active power lower limit value as much as possible when the extremely low power target is reached;

[0087] Wait for the completion of this control and then enter S103;

[0088] (2) If P target >P currentmin， Then control to start a specific model inverter and determine the power target value P of the grid dispatching power target and the current total active power lower limit P currentmin and the lower limit value P of the first pre-start unit prestartmin The size of the sum, where P prestartmin The lower limit value of the active power of the model inverter corresponding to the top element of the current shutdown stack;

[0089] ①When P target >P currentmin +P prestartmin When P target >P currentmin +P prestartmin When the startup stack and shutdown stack are updated and a sample inverter is started, P is recalculated. currentmin and P prestartmin , and judge whether P is still satisfied target >P currentmin +P prestartmin If P target >P currentmin +P prestartmin , then continue to update the startup stack and shutdown stack, start a sample inverter, and continue to recalculate P currentmin and P prestartmin , and judge whether P is still satisfied target >P currentmin +P prestartmin , until P target ≤P currentmin +P prestartmin Or the shutdown stack is empty;

[0090] The updating of the startup stack and the shutdown stack and starting a model inverter is specifically performed as follows: popping out a model inverter element at the top of the shutdown stack, pushing the popped-out model inverter element to the top of the startup stack, and starting the model inverter corresponding to the newly pushed-in top element of the startup stack;

[0091] The continued recalculation of P currentmin and P prestartmin , and judge whether P is still satisfied target >P currentmin +P prestartmin The specific operation is: recalculate the sum of the lower limit values of active power of all model inverters corresponding to all elements of the current startup stack after update P currentmin The active lower limit value P of the model inverter corresponding to the top element of the current shutdown stack prestartmin，Then, it is judged whether the condition of P is satisfied target >P currentmin +P prestartmin is met;

[0092] Due to the principle of last-in, first-out of the stack, the elements in the shutdown stack are pushed into the stack in the order from large to small according to the active power lower limit value of the template inverter. When popping, it just makes the elements pop out of the stack in the order from small to large according to the active power lower limit value of the template inverter. When popping into the startup stack, it also just makes the elements pushed into the stack in the order from small to large according to the active power lower limit value of the template inverter. This ensures that the startup order of the template inverters starts from small to large according to the active power lower limit value of the template inverter, and preferentially starts the template inverters with smaller active power lower limit values of the template inverters; it can make the template inverters operate normally above the active power lower limit value as much as possible when the low-power target is reached;

[0093] After waiting for the completion of the execution of this control, enter S103;

[0094] ② When P target ≤P currentmin +P prestartmin , then do not start any template inverters and enter S103;

[0095] S103: Perform equal-margin active power distribution on all template inverters in the startup stack and perform active power regulation control. After waiting for the completion of the execution of this control, return to S4.

[0096] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for coordinated control of active power of two types of inverters during the power limit period of a photovoltaic power station, characterized in that: S1: Set the coordinated control function switch; S2: Determine whether the coordinated control switch is turned on; if the coordinated control switch is in the on state, go to S3; if the coordinated control function switch is in the off state, return to S2; S3: Obtain the characteristic information of the inverters in the photovoltaic power station, and divide the inverters into non-template inverters and template inverters; control the initial state of the template inverters to be not in the AGC state, control the initial state of the non-template inverters to be in the AGC state, and establish a startup stack and a shutdown stack, where the initial values of the elements are all assigned as empty; S4: Real-time collect the active power target value P of the power grid dispatching target , determine the magnitude relationship between the active power target value of the power grid dispatching and the total capacity of the sample inverters. If the active power target value of the power grid dispatching is greater than or equal to the total capacity of the sample inverters, proceed to S5; if the active power target value of the power grid dispatching is less than the total capacity of the sample inverters, proceed to step S6; S5: Perform relevant control for the template inverters to exit the AGC. After waiting for the completion of this control, return to S4; S6: Select a non-template inverter with coordinated regulation function and a template inverter with coordinated regulation function; Calculate the total actual active power value of all the template inverters except the template inverter with coordinated regulation function, denoted as P1; Calculate the difference between the sum of the active power that can be generated by the non-template inverter with coordinated regulation function and the total active power that can be generated by all template inverters and the correction margin value, denoted as P2; determine whether the condition P1 < P target < P2 is satisfied. If it is satisfied, it is determined that the template inverter and the non-template inverter need to jointly control the active power, and go to S7; if it is not satisfied, it is determined that the template inverter and the non-template inverter do not need to jointly control the active power, and then judge P target The relationship with P1 and P2. If P target ≤ P1, go to S8. If P target ≥ P2, return to S5; S7: Perform pre-control for the coordinated control of the template inverters and non-template inverters. After waiting for the completion of this control, enter S9; S8: Perform pre-control for the independent template inverters. After waiting for the completion of this control, enter S10; S9: Perform AGC control in the coordinated mode of the template inverters and non-template inverters. After waiting for the completion of this operation, return to S4; S10: Perform AGC control with the independent participation of the template inverters. After waiting for the completion of this control, return to S4.

2. A method for collaborative control of active power of two types of inverters during the power limit period of a photovoltaic power station, characterized in that, The establishment of the startup stack and the shutdown stack includes: Establish a startup stack for storing the elements of the template inverters that are turned on and an element of a non-template inverter during the AGC control process of the template inverters. Among them, the initial value of the startup stack element is assigned as empty; an element of a non-template inverter is the non-template inverter with the smallest active power lower limit among the non-template inverters; where the active power lower limit is an inherent characteristic of the inverter, that is, the minimum active power for the inverter to maintain normal operation, and it is a set fixed value; Establish a shutdown stack for storing the elements of the template inverters that are shut down during the AGC control process of the template inverters, where the initial value of the shutdown stack element is assigned as empty.

3. A method for coordinated control of active power of two types of inverters during power limit of a photovoltaic power station according to claim 1, characterized in that, The S5 includes: Determine whether the template inverters have been put into the AGC. If the template inverters have not been put into the AGC, maintain the maximum power mode operation of the template inverters, and the non-template inverters participate in the AGC regulation of the active power; if the template inverters have been put into the AGC, control the template inverters to exit the AGC. When the shutdown stack is not empty, start all the template inverters in the shutdown stack and control them to operate in the maximum power mode, clear the startup stack and the shutdown stack, and control the non-template inverters to participate in the AGC regulation of the active power.

4. A method for coordinated control of active power of two types of inverters during the limited power period of a photovoltaic power station, characterized in that, The S6 includes: Select a non - reference inverter with the smallest active power lower limit among non - reference inverters as the non - reference inverter for coordinated regulation; select a reference inverter with the largest active power lower limit among reference inverters as the reference inverter for coordinated regulation. Herein, the active power lower limit of each inverter is an inherent characteristic of each inverter, that is, the minimum active power for the inverter to maintain normal operation, which is a set fixed value; Calculate P1 = the total actual active power generation value of all reference inverters except the reference inverter for coordinated regulation; calculate P2 = the available active power of the non - reference inverter for coordinated regulation+the total available active power of all reference inverters - the correction margin value. Among them, the available active power can be calculated according to the light intensity and temperature of the photovoltaic power station, and the correction margin value is a set fixed value; Judge whether the condition of P1 < P target < P2 is satisfied. If it is satisfied, it is determined that the template inverter and the non-template inverter need to cooperate to control the active power, and enter S7 to perform the pre-control of the cooperative control of the template inverter and the non-template inverter. If it is not satisfied, it is determined that the template inverter and the non-template inverter do not need to cooperate to control the active power, and then judge P target The relationship with P1 and P2. If P target ≤ P1, enter S8 to perform the pre-control of the independent template inverter control. If P target ≥ P2, return to S5 to perform the relevant control for the template inverter to exit AGC.

5. A method for coordinated control of active power of two types of inverters during the limited power period of a photovoltaic power station, characterized in that, The pre - control of the coordinated control of the reference inverter and non - reference inverter includes: Judge whether the reference inverter has been put into AGC control. If the reference inverter has not been put into AGC control, push all reference inverter elements onto the top of the startup stack in ascending order of the active power lower limit of the reference inverter, put all reference inverters into AGC control, and push the non - reference inverter element for coordinated regulation onto the top of the startup stack; if the reference inverter has been put into AGC control, judge whether the shutdown stack is empty; If the shutdown stack is not empty, pop the reference inverter elements from the top of the shutdown stack in turn and push them onto the top of the startup stack. For each popped reference inverter element, start the reference inverter until the shutdown stack is empty. Finally, push the non - reference inverter element for coordinated regulation onto the top of the startup stack; if the shutdown stack is empty, when the inverter element at the top of the startup stack is not the non - reference inverter element for regulation function, push the non - reference inverter element for coordinated regulation onto the top of the startup stack.

6. A method for coordinated control of active power of two types of inverters during the power limit period of a photovoltaic power station, characterized in that, The pre - control of the independent reference inverter control includes: Judge whether the reference inverter has been put into AGC control. If the reference inverter has not been put into AGC control, push the corresponding elements of all reference inverters onto the top of the startup stack in ascending order of the active power lower limit of the reference inverter, and put all reference inverters into AGC control; if the reference inverter has been put into AGC control, when the element at the top of the startup stack is the non - reference inverter element for coordinated regulation, pop the element at the top of the startup stack.

7. A method for coordinated control of active power of two types of inverters during power limit of a photovoltaic power station according to claim 1, characterized in that, The AGC control in the coordinated mode of the reference inverter and non - reference inverter includes: S91: When the non - reference inverter for coordinated regulation is shut down, control to start the non - reference inverter for coordinated regulation; S92: Stop all non - reference inverters that are not shut down except the non - reference inverter for coordinated regulation; S93: Perform AGC control on all inverters in the startup stack in a coordinated manner. The specific steps are as follows: For the inverters corresponding to the first and second elements at the top of the startup stack, perform equal-margin active power distribution and control, that is, perform equal-margin active power distribution and control on the non-template inverters and template inverters for coordinated regulation; control the inverters corresponding to the remaining elements in the startup stack except the first and second elements at the top, that is, control all the remaining template inverters except the template inverters corresponding to the template inverter elements for coordinated regulation, and control the above-mentioned all remaining template inverters to generate electricity in the maximum power mode.

8. A method for collaborative control of active power of two types of inverters during the power limit period of a photovoltaic power station, characterized in that, The AGC control independently participated by the template inverters includes: S101: Stop all started non-template inverters; S102: Control the startup and shutdown of the template inverter. The specific steps are as follows: Determine the grid dispatching active power target value P target and the current total active power lower limit value P currentmin . Here, the current total active power lower limit value is the sum of the active power lower limit values of the template inverters corresponding to all elements in the current startup stack. If P target ≤P currentmin , then control to stop a specific template inverter, and wait until this control is completed and then enter S103. If P target >P currentmin , then determine the grid dispatching power target value P target and the sum of the current total active power lower limit value P currentmin and the active power lower limit value P prestartmin of the first pre-startup unit. Here, P prestartmin is the active power lower limit value of the template inverter corresponding to the top element of the current shutdown stack. When P target > P currentmin + P prestartmin , then control starts a specific template inverter. After waiting for the completion of this control, it enters S103; when P target ≤ P currentmin + P prestartmin , then do not start any template inverter and enter S103; S103: Perform equal-margin active power distribution on all template inverters in the startup stack and perform active power regulation control. After waiting for the completion of this control, return to S4.

9. According to claim 8, characterized in that, The control to stop specific template inverters includes: When P target ≤ P currentmin then update the startup stack and the shutdown stack, and stop one sample inverter, recalculate P currentmin and determine whether it still satisfies P target ≤ P currentmin ; if P target ≤ P currentmin， then continue to update the startup stack and the shutdown stack, and stop one sample inverter, continue to recalculate P currentmin and determine whether it still satisfies P target ≤ P currentmin， until P target > P currentmin or the startup stack is empty; Among them, the specific operation of updating the startup stack and the shutdown stack and stopping one template inverter is as follows: Pop a template inverter element at the top of the startup stack, and push the popped template inverter element onto the top of the shutdown stack, and stop the template inverter corresponding to the newly pushed element at the top of the shutdown stack; The recalculated P currentmin and determine whether it still satisfies P target ≤P currentmin， The specific operation is as follows: Recalculate the sum P of the active power lower limit values of the template inverters corresponding to all elements of the currently powered-on stack after the update currentmin , and then re-determine whether it satisfies P target ≤P currentmin condition.

10. According to claim 8, wherein The control to start specific template inverters includes: When P target > P currentmin + P prestartmin , update the startup stack and the shutdown stack and start a sample inverter, recalculate P currentmin and P prestartmin , and determine whether it still satisfies P target > P currentmin + P prestartmin ; if P target > P currentmin + P prestartmin , then continue to update the startup stack and the shutdown stack, and start a sample inverter, continue to recalculate P currentmin and P prestartmin , and determine whether it still satisfies P target > P currentmin + P prestartmin , until P target ≤ P currentmin + P prestartmin or the shutdown stack is empty; Among them, the specific operation of updating the startup stack and the shutdown stack and starting one template inverter is as follows: Pop a template inverter element at the top of the shutdown stack, and push the popped template inverter element onto the top of the startup stack, and start the template inverter corresponding to the newly pushed element at the top of the startup stack; The continued recalculation of P currentmin and P prestartmin , and determine whether it still satisfies P target > P currentmin + P prestartmin , and the specific operation is: recalculate the sum P currentmin of the active power lower limit values of all elements in the current startup stack after update corresponding to the sample inverter prestartmin and the active power lower limit value P target > P currentmin + P prestartmin .

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