A photovoltaic power station grid-connected stable control system, a control method thereof and a stable control device

Abstract

The present application relates to the field of electric power technology, discloses a kind of photovoltaic power station grid-connected stable control system and its control method, stable control device.The present application is by stable control device, the photovoltaic array corresponding to each inverter interface controller connected is divided into machine group and modulation group, all photovoltaic arrays in modulation group are divided into multiple sub photovoltaic array groups;Determine controllable capacity information and send to upper stable control system;Receive the stable control instruction sent by upper stable control system according to the controllable capacity information and corresponding unstable operating condition when corresponding power system fails;If the stable control instruction is machine trip instruction, send the photovoltaic array command of cutting off to the inverter interface controller corresponding to machine group;If the stable control instruction is modulation instruction, then send the stable control power fast modulation command to the inverter interface controller corresponding in turns.The present application can improve the flexibility of stable control, avoid power waste.

Description

Technical Field

[0001] This invention relates to the field of power technology, and in particular to a grid-connected stability control system for a photovoltaic power station, as well as its control method and stability control device. Background Technology

[0002] The grid-connected stability control system of a photovoltaic power plant includes a stability control device installed within the photovoltaic power plant, a higher-level stability control system, and an inverter interface controller. The inverter interface controller is connected to the corresponding photovoltaic array via cable communication. The main function of the stability control device is to ensure the stability of the power system when encountering large disturbances. In the event of severe faults such as DC fault blocking or AC transmission channel interruption, it addresses the safety and stability of the power grid by taking measures such as generator tripping, load shedding, and emergency DC power boosting or reduction.

[0003] Compared to traditional power stabilization devices, existing photovoltaic (PV) power plant stabilization devices offer the functions of directly disconnecting the PV array and quickly adjusting the stabilization power. When performing quick power adjustment, the inverter interface controller rapidly adjusts the power output of all PV power plants to the minimum power of 0.1 pu. The advantage of disconnecting the PV array is its speed; after directly tripping the corresponding grid connection switch, the power output of the PV inverter can instantly become zero. The disadvantage is that restoring the system to its pre-fault operating state is more complicated, as the PV power plant must reconnect to the grid and the switch must be re-closed. The advantage of the quick power adjustment function is its convenience and speed in restoring the system to its pre-fault operating state; after a fault, directly resetting the inverter interface controller quickly increases the PV inverter power to its pre-fault level. The disadvantage is that the adjustment speed of the entire process is significantly slower than the strategy of directly disconnecting the PV array.

[0004] The stability control device within a photovoltaic power station is equipped with a control word, the value of which is manually set to 0 or 1 based on actual conditions. When implementing remote stability control strategies, the existing stability control device in a photovoltaic power station performs generator tripping / power modulation functions according to instructions from the superior stability control system. Specifically, if the control word is set to 0, it indicates that the corresponding stability control device is in "modulation" mode. Upon receiving an instruction from the superior stability control system to disconnect the photovoltaic power station units, the stability control device performs a fast adjustment of the stability control power. If the control word is set to 1, it indicates that the corresponding stability control device is in "disconnection" mode. Upon receiving an instruction from the superior stability control system to disconnect the photovoltaic power station units, the stability control device performs a direct disconnection of the photovoltaic array, thereby directly tripping the corresponding grid connection point (feeder, low-voltage side of the main transformer, etc.) switch.

[0005] However, for large disturbances in the power system, such as severe instability conditions like power angle instability, a strategy of directly disconnecting the photovoltaic array is preferable. For small disturbances in the power system, such as frequency instability, voltage instability, and line overload, a strategy of fast power regulation should be adopted. Existing stability control devices in photovoltaic power plants, when implementing remote stability control strategies, simply determine whether to directly disconnect the photovoltaic array or implement fast power regulation based on the values ​​configured in the control word. This results in a lack of flexibility in stability control, and when implementing fast power regulation, it directly adjusts the power output of all photovoltaic power plants, easily leading to power waste. Summary of the Invention

[0006] This invention provides a grid-connected stability control system and its control method and device for photovoltaic power plants. It solves the technical problems of existing photovoltaic power plant stability control methods, which directly determine whether to directly cut off the photovoltaic array or perform fast adjustment of the stability control power based on the value configured by the control word. This results in a lack of flexibility in stability control, and when performing fast adjustment of the stability control power, the power output of all photovoltaic power plants is directly adjusted, which easily leads to power waste.

[0007] The first aspect of this invention provides a control method for a grid-connected stability control system of a photovoltaic power plant, applied to a stability control device. The stability control device is connected to a higher-level stability control system and an inverter interface controller, and each inverter interface controller is connected to a corresponding photovoltaic array. The method includes:

[0008] Determine the photovoltaic array corresponding to each connected inverter interface controller, divide all photovoltaic arrays into switching groups and modulation groups, and divide all photovoltaic arrays in the modulation group into multiple sub-photovoltaic array groups;

[0009] The system receives the active power of the photovoltaic arrays sent by the interface controllers of each connected inverter, determines the controllable capacity information based on the active power, and sends it to the upper-level stability control system. The controllable capacity information includes the maximum switchable capacity of the photovoltaic array corresponding to the switching unit and the maximum modulated capacity of the photovoltaic array corresponding to each sub-photovoltaic array group.

[0010] The system receives a stability control command sent by the upper-level stability control system when a fault occurs in the corresponding power system; the stability control command is generated by the upper-level stability control system based on the controllable capacity information and the instability condition corresponding to the fault in the corresponding power system.

[0011] If the stability control command is a tripping command, a photovoltaic array cutoff command is sent to the inverter interface controller corresponding to the tripping group according to the tripping command, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; if the stability control command is a modulation command, according to the order of each of the sub-photovoltaic array groups in the modulation group, a stability control power fast adjustment command is sent to the corresponding inverter interface controller in rounds, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array.

[0012] According to one achievable method of the first aspect of the present invention, the tripping command includes the required tripping capacity, and the step of sending a tripping command to the inverter interface controller corresponding to the tripping unit according to the tripping command includes:

[0013] Select photovoltaic arrays from the cut-off units and add them to the set of photovoltaic arrays to be cut, until the total modulotable capacity of the photovoltaic arrays in the set of photovoltaic arrays to be cut reaches the required cut-off capacity;

[0014] Send a command to disconnect the photovoltaic array to the inverter interface controller corresponding to each of the photovoltaic arrays that need to be disconnected.

[0015] According to one aspect of the invention, in a manner achievable by the first claim, the photovoltaic arrays in the switching unit are configured with switching priorities, and the step of selecting a photovoltaic array from the switching unit and adding it to the set of photovoltaic arrays to be switched includes:

[0016] Photovoltaic arrays are selected from the switching groups in descending order of priority and added to the set of photovoltaic arrays to be switched.

[0017] According to one achievable method of the first aspect of the present invention, dividing all photovoltaic arrays in the modulation group into multiple sub-photovoltaic array groups includes:

[0018] Obtain the modulation priority of all photovoltaic arrays in the modulation group;

[0019] All photovoltaic arrays in the modulation group are sorted in descending order of modulation priority to obtain a sorted photovoltaic array sequence.

[0020] The sorted photovoltaic array sequence is divided into multiple sub-photovoltaic array groups.

[0021] According to one achievable method of the first aspect of the present invention, the modulation command includes the required modulation capacity, and the step of sending a stabilization power fast adjustment command to the corresponding inverter interface controller in rounds according to the order of each of the sub-photovoltaic array groups in the modulation group includes:

[0022] Send a power stabilization command to the inverter interface controller corresponding to the first group of sub-photovoltaic arrays arranged in the modulation group;

[0023] The power regulation amount for the current cycle is calculated based on the actual power regulation amount fed back by the corresponding inverter interface controller, and the cumulative power regulation amount is updated based on the calculated power regulation amount for the current cycle.

[0024] Determine whether the new cumulative power adjustment amount has reached the required modulation capacity; if yes, determine that the modulation command has been completed and end the current stabilization power fast adjustment; if no, send the stabilization power fast adjustment command to the inverter interface controller corresponding to the next group of sub-photovoltaic arrays in the modulation group and return to the previous step.

[0025] According to one embodiment of the first aspect of the present invention, the stabilization device is provided with a control word, and the method further includes:

[0026] When the local stability control strategy is triggered, if the current control word is set to 1, a command to disconnect the photovoltaic array is sent to the inverter interface controller corresponding to the disconnected unit, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; if the current control word is set to 0, according to the order of each of the sub-photovoltaic array groups in the modulation group, a power stabilization fast adjustment command is sent to the corresponding inverter interface controller in rounds, so that the corresponding inverter interface controller modulates the power of the corresponding photovoltaic array; the execution of the local stability control strategy includes the execution of high-frequency, low-frequency disconnection or fault disconnection actions.

[0027] A second aspect of the present invention provides a stabilization control device for a grid-connected stability control system of a photovoltaic power station. The stabilization control device is connected to an upper-level stabilization control system and an inverter interface controller, and each inverter interface controller is connected to a corresponding photovoltaic array. The stabilization control device includes:

[0028] A memory for storing instructions; wherein the instructions are used to implement the control method of the photovoltaic power plant grid-connected stability control system as described in any of the above-mentioned methods;

[0029] A processor for executing instructions in the memory.

[0030] A third aspect of the present invention provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, which, when executed by a processor, implements the control method of the photovoltaic power plant grid-connected stability control system as described in any of the above embodiments.

[0031] A fourth aspect of the present invention provides a stabilization control device for a grid-connected stability control system of a photovoltaic power station. The stabilization control device is connected to an upper-level stabilization control system and an inverter interface controller. Each inverter interface controller is connected to a corresponding photovoltaic array. The stabilization control device includes:

[0032] The photovoltaic array partitioning module is used to determine the photovoltaic arrays corresponding to each connected inverter interface controller, divide all photovoltaic arrays into switching groups and modulation groups, and divide all photovoltaic arrays in the modulation group into multiple sub-photovoltaic array groups.

[0033] The controllable capacity reporting module is used to receive the active power of the photovoltaic array sent by the interface controllers of each connected inverter, determine the controllable capacity information based on the active power, and send it to the upper-level stability control system; the controllable capacity information includes the maximum switchable capacity of the photovoltaic array corresponding to the switching unit and the maximum modulated capacity of the photovoltaic array corresponding to each sub-photovoltaic array group.

[0034] The stability control command receiving module is used to receive stability control commands sent by the upper-level stability control system when a fault occurs in the corresponding power system; the stability control commands are generated by the upper-level stability control system based on the controllable capacity information and the instability conditions corresponding to the fault in the corresponding power system.

[0035] The stability control command execution module is used to send a photovoltaic array cutoff command to the inverter interface controller corresponding to the cutoff group when the stability control command is a cutoff command, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; when the stability control command is a modulation command, it sends a stability control power fast adjustment command to the corresponding inverter interface controller in rounds according to the order of each of the sub-photovoltaic array groups in the modulation group, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array.

[0036] According to one embodiment of the fourth aspect of the present invention, the cut-off command includes the required cut-off capacity, and the stability control command execution module includes:

[0037] The selection unit is used to select a photovoltaic array from the cut-off unit and add it to the set of photovoltaic arrays to be cut, until the total modulable capacity of the photovoltaic arrays in the set of photovoltaic arrays to be cut reaches the required cut-off capacity.

[0038] The first sending unit is used to send a command to cut off the photovoltaic array to the inverter interface controller corresponding to each of the photovoltaic arrays that need to be cut off.

[0039] According to one embodiment of the fourth aspect of the present invention, the photovoltaic array in the switching unit is configured with a switching priority, and the selection unit is specifically used for:

[0040] Photovoltaic arrays are selected from the switching groups in descending order of priority and added to the set of photovoltaic arrays to be switched.

[0041] According to one achievable embodiment of the fourth aspect of the present invention, the photovoltaic array partitioning module comprises:

[0042] An acquisition unit is used to acquire the modulation priority of all photovoltaic arrays in the modulation group;

[0043] The sorting unit is used to sort all the photovoltaic arrays in the modulation group in descending order of modulation priority to obtain a sorted photovoltaic array sequence.

[0044] A partitioning unit is used to divide the sorted photovoltaic array sequence into multiple sub-photovoltaic array groups.

[0045] According to one embodiment of the fourth aspect of the present invention, the modulation instruction includes a modulation capacity, and the stabilization instruction execution module includes:

[0046] The second transmitting unit is used to send a power stabilization fast adjustment command to the inverter interface controller corresponding to the first group of sub-photovoltaic arrays arranged in the modulation group.

[0047] The calculation and update unit is used to calculate the power regulation amount of the current cycle based on the actual power regulation amount fed back by the corresponding inverter interface controller, and update the cumulative power regulation amount based on the calculated power regulation amount of the current cycle.

[0048] The loop execution unit is used to determine whether the new cumulative power adjustment amount has reached the required modulation capacity; if yes, it determines that the modulation instruction has been completed and ends the current stabilization power fast adjustment; if no, it sends the stabilization power fast adjustment command to the inverter interface controller corresponding to the next group of sub-photovoltaic arrays in the modulation group and returns to the previous step.

[0049] According to one embodiment of the fourth aspect of the present invention, the stabilization device includes a control word, and the stabilization device further includes:

[0050] The local execution module is used to, when triggered to execute the local stability control strategy, send a photovoltaic array cut-off command to the inverter interface controller corresponding to the cut-off unit if the current control word is set to 1, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; if the current control word is set to 0, send a power stabilization fast adjustment command to the corresponding inverter interface controller in rounds according to the order of each of the sub-photovoltaic array groups in the modulation group, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array; the execution of the local stability control strategy includes executing high-frequency, low-frequency disconnection or fault disconnection actions.

[0051] The fifth aspect of the present invention provides a grid-connected stability control system for a photovoltaic power plant, characterized in that it includes an upper-level stability control system, an inverter interface controller, and a stability control device for the grid-connected stability control system of the photovoltaic power plant as described in any of the above embodiments.

[0052] As can be seen from the above technical solutions, the present invention has the following advantages:

[0053] This invention uses a stability control device to divide the photovoltaic arrays corresponding to the interface controllers of each connected inverter into a tripping group and a modulation group. All photovoltaic arrays in the modulation group are further divided into multiple sub-photovoltaic array groups. The controllable capacity information is determined and sent to the upper-level stability control system. The invention receives stability control commands from the upper-level stability control system based on the controllable capacity information and the corresponding instability condition when a fault occurs in the corresponding power system. If the stability control command is a tripping command, a command to disconnect the photovoltaic array is sent to the inverter interface controller corresponding to the tripping group. If the stability control command is a modulation command, a fast-adjustment command for stable power is sent to the corresponding inverter interface controller in batches. When executing a remote stability control strategy, the upper-level stability control system sends corresponding stability control commands based on the controllable capacity information and the corresponding instability condition to determine whether to perform tripping or modulation, improving the flexibility of stability control. Furthermore, when performing power modulation, the modulation commands are executed in a refined batch manner, avoiding power waste. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A flowchart of a control method for a grid-connected stability control system of a photovoltaic power plant, provided as an optional embodiment of the present invention;

[0056] Figure 2 A flowchart of a control method for a photovoltaic power plant grid-connected stability control system is provided as another optional embodiment of the present invention;

[0057] Figure 3 Provided as an optional embodiment of the present invention Figure 2 The diagram shows the control principle of the method shown.

[0058] Figure 4 The diagram below shows the structural connection of a stabilization device in a grid-connected stability control system for a photovoltaic power plant, provided as an optional embodiment of the present invention.

[0059] Figure 5 The diagram below shows the structural connection of a stabilization device in a photovoltaic power plant grid-connected stability control system, which is provided as another optional embodiment of the present invention.

[0060] Figure label:

[0061] 1- Photovoltaic array partitioning module; 2- Controllable capacity reporting module; 3- Stabilization command receiving module; 4- Stabilization command execution module; 5- Local execution module. Detailed Implementation

[0062] This invention provides a grid-connected stability control system and its control method and device for photovoltaic power plants. It addresses the technical problems of existing photovoltaic power plant stability control methods, which directly determine whether to directly disconnect the photovoltaic array or perform fast power adjustment based on the value configured in the control word. This results in a lack of flexibility in stability control, and when fast power adjustment is performed, it directly adjusts the power output of all photovoltaic power plants, which can easily lead to power waste.

[0063] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0064] This invention provides a control method for a grid-connected stability control system of a photovoltaic power plant. The method is applied to a stability control device, which is connected to a higher-level stability control system and an inverter interface controller. Each inverter interface controller is connected to a corresponding photovoltaic array.

[0065] Please see Figure 1 , Figure 1 A flowchart of a control method for a grid-connected stability control system for a photovoltaic power plant, provided by an embodiment of the present invention, is shown.

[0066] This invention provides a control method for a photovoltaic power plant grid-connected stability control system, comprising:

[0067] Step S1: Determine the photovoltaic array corresponding to each connected inverter interface controller, divide all photovoltaic arrays into switching groups and modulation groups, and divide all photovoltaic arrays in the modulation group into multiple sub-photovoltaic array groups.

[0068] In this embodiment, all photovoltaic arrays are divided into two parts: one part is used to execute the switching command, and the other part is used to execute the modulation command. The division of the switching and modulation groups can be done by the stability control device in a random manner, or the stability control device can divide the switching and modulation groups according to pre-stored preset photovoltaic array division rules or obtain preset photovoltaic array division rules.

[0069] In one feasible manner, dividing all photovoltaic arrays in the modulation group into multiple sub-photovoltaic array groups includes:

[0070] Obtain the modulation priority of all photovoltaic arrays in the modulation group;

[0071] All photovoltaic arrays in the modulation group are sorted in descending order of modulation priority to obtain a sorted photovoltaic array sequence.

[0072] The sorted photovoltaic array sequence is divided into multiple sub-photovoltaic array groups.

[0073] In this embodiment, all photovoltaic arrays in the modulation group are sorted according to their modulation priority from high to low. Then, the sorted photovoltaic array sequence is divided into sub-photovoltaic array groups. This allows subsequent steps to prioritize the sub-photovoltaic array groups with higher overall modulation priority for fast power adjustment, achieving fine modulation and improving the accuracy of power regulation.

[0074] When dividing the sorted photovoltaic array sequence into multiple sub-photovoltaic array groups, it can be done through random or equal division. For random or equal division, the number of groups is preset, and the division is then performed based on the number of groups.

[0075] In another feasible approach, the photovoltaic array sequence can be divided according to the region to which it belongs, grouping photovoltaic array sequences belonging to the same specific region into the same sub-photovoltaic array group. This can improve the efficiency of fast adjustment of stable power.

[0076] It should be noted that, in other feasible methods, all photovoltaic arrays in the modulation group can also be randomly divided into multiple sub-photovoltaic array groups.

[0077] Step S2: Receive the active power of the photovoltaic array sent by the interface controllers of each connected inverter, determine the controllable capacity information based on the active power, and send it to the upper-level stability control system; the controllable capacity information includes the maximum switchable capacity of the photovoltaic array corresponding to the switching unit and the maximum modulated capacity of the photovoltaic array corresponding to each sub-photovoltaic array group.

[0078] In this embodiment, sending the controllable capacity information to the upper-level stability control system facilitates the upper-level system in determining the required switching capacity / modulation capacity based on the controllable capacity information. For example, when the upper-level stability control system calculates the theoretical required switching capacity / modulation capacity according to relevant rules, if the theoretical required switching capacity / modulation capacity is greater than the corresponding controllable capacity, then the corresponding controllable capacity is used as the actual required switching capacity / modulation capacity, thereby generating a stability control command based on the actual required switching capacity / modulation capacity.

[0079] It should be noted that the corresponding rules or methods for calculating the theoretical required switching capacity / modulation capacity can refer to existing calculation methods, and are not limited in this embodiment.

[0080] Step S3: Receive the stability control command sent by the upper-level stability control system when a fault occurs in the corresponding power system; the stability control command is generated by the upper-level stability control system based on the controllable capacity information and the instability condition corresponding to the fault in the corresponding power system.

[0081] In this embodiment, the determination of whether to perform a power grid trip or modulation is made by the upper-level stability control system based on the instability condition corresponding to the power system fault. For large disturbances in the power system, such as power angle instability, a strategy of directly cutting off the photovoltaic array is preferable; for small disturbances, such as frequency instability, voltage instability, and line overload, a strategy of rapid power adjustment should be adopted. Referring to this, as a specific implementation, in this embodiment, when the instability condition corresponding to the power system fault is a relatively severe instability condition such as power angle instability, the stability control command generated is a power grid trip command; while when the instability condition corresponding to the power system fault is a condition such as frequency instability, voltage instability, or line overload, the stability control command generated is a modulation command.

[0082] Step S4: If the stability control command is a tripping command, a photovoltaic array cutoff command is sent to the inverter interface controller corresponding to the tripping group according to the tripping command, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; if the stability control command is a modulation command, according to the order of each sub-photovoltaic array group in the modulation group, a stability control power fast adjustment command is sent to the corresponding inverter interface controller in rounds, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array.

[0083] In existing technologies, rapid power modulation is not phased; that is, regardless of whether the fault is severe or minor, the entire photovoltaic power station's power is directly reduced to the minimum. This approach lacks precision and easily leads to power waste. For example, for some minor instability conditions, adjusting the power of only a portion of the photovoltaic array can achieve stable and safe system control. Using existing modulation methods results in significant power waste. In this embodiment, according to the order of the sub-photovoltaic arrays in the modulation group, rapid power adjustment commands are sent to the corresponding inverter interface controllers in phases, improving the precision of stability control and effectively avoiding power waste.

[0084] In one feasible implementation, the tripping command includes the required tripping capacity, and the step of sending a photovoltaic array tripping command to the inverter interface controller corresponding to the tripping unit according to the tripping command includes:

[0085] Select photovoltaic arrays from the cut-off units and add them to the set of photovoltaic arrays to be cut, until the total modulotable capacity of the photovoltaic arrays in the set of photovoltaic arrays to be cut reaches the required cut-off capacity;

[0086] Send a command to disconnect the photovoltaic array to the inverter interface controller corresponding to each of the photovoltaic arrays that need to be disconnected.

[0087] In a specific implementation, photovoltaic arrays can be selected from the photovoltaic arrays to be switched in descending order of priority.

[0088] In the above embodiments of the present invention, the photovoltaic arrays to be cut off are predetermined based on the required capacity, and then a command to cut off the photovoltaic array is sent to the inverter interface controller corresponding to the photovoltaic array to be cut off, thereby realizing the execution of the cut-off command. The photovoltaic arrays to be cut off are selected in descending order of cut-off priority, which allows for more precise cut-off and improves the flexibility of stable control.

[0089] In other feasible methods, a photovoltaic array cutoff command can be sequentially sent to the inverter interface controllers corresponding to the photovoltaic arrays in the unit being cut off. The actual number of photovoltaic arrays cut off, reported by each inverter interface controller, can be tallied. It can then be determined whether the tallied actual number of cutoffs reaches the required cutoff capacity. If it does, the sending of the photovoltaic array cutoff command can be stopped. In this embodiment, the execution process of the cutoff command is relatively long, but because the decision to continue sending photovoltaic array cutoff commands to the inverter interface controllers corresponding to other photovoltaic arrays is based on the actual number of cutoffs, the accuracy of the cutoff can be improved.

[0090] In one feasible implementation, the modulation command includes the required modulation capacity, and the step of sending a stabilization power fast adjustment command to the corresponding inverter interface controller in rounds according to the order of each of the sub-photovoltaic array groups in the modulation group includes:

[0091] Send a power stabilization command to the inverter interface controller corresponding to the first group of sub-photovoltaic arrays arranged in the modulation group;

[0092] The power regulation amount for the current cycle is calculated based on the actual power regulation amount fed back by the corresponding inverter interface controller, and the cumulative power regulation amount is updated based on the calculated power regulation amount for the current cycle.

[0093] Determine whether the new cumulative power adjustment amount has reached the required modulation capacity; if yes, determine that the modulation command has been completed and end the current stabilization power fast adjustment; if no, send the stabilization power fast adjustment command to the inverter interface controller corresponding to the next group of sub-photovoltaic arrays in the modulation group and return to the previous step.

[0094] For example, the modulation group has four sub-photovoltaic array groups. According to this embodiment, when a modulation command is received from the upper-level stability control system, the first to the fourth groups perform power modulation in rounds. When the power adjustment amount required by the upper-level stability control system is met, the power adjustment stops.

[0095] In other feasible methods, when sending the power regulation command to the corresponding inverter interface controller in rounds according to the order of each sub-photovoltaic array group in the modulation group, the sub-photovoltaic array group that needs to be modulated can also be pre-determined according to the required modulation capacity, so that the power modulation is performed in rounds according to the order of the sub-photovoltaic array group that needs to be modulated in the modulation group.

[0096] The above embodiments of the present invention illustrate specific implementation methods for the stabilization control device to execute a remote stabilization control strategy. In one feasible implementation, the stabilization control device is equipped with a control word, such as... Figure 2 As shown, in Figure 1 Based on the method shown, the method further includes:

[0097] Step S5: When the local stabilization control strategy is triggered, if the current control word is set to 1, a command to disconnect the photovoltaic array is sent to the inverter interface controller corresponding to the disconnected unit, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; if the current control word is set to 0, according to the order of each of the sub-photovoltaic array groups in the modulation group, a power stabilization fast adjustment command is sent to the corresponding inverter interface controller in rounds, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array; the execution of the local stabilization control strategy includes the execution of high-frequency, low-frequency disconnection or fault disconnection actions.

[0098] In this embodiment, referencing existing methods for selecting switching and rapid power modulation based on control words, a new specific implementation method for the local stabilization control strategy executed by the stability control device is added. The control word is manually set by the operator. The control word setting is only used to select switching or power modulation functions when the stability control device executes its own local stabilization control strategy (i.e., high-frequency, low-frequency disconnection, or fault disconnection). The selection of switching / power modulation for the remote stabilization control strategy is determined by the upper-level stability control system and is independent of the control word. The relevant control principles are as follows: Figure 3 As shown.

[0099] The present invention also provides a stabilization control device for a photovoltaic power plant grid-connected stability control system. The stabilization control device is connected to an upper-level stabilization control system and an inverter interface controller. Each inverter interface controller is connected to a corresponding photovoltaic array. The stabilization control device can be used to execute the control method of the photovoltaic power plant grid-connected stability control system described in any of the above embodiments of the present invention.

[0100] Please see Figure 4 , Figure 4 The diagram shows the structural connection of a stabilization device in a photovoltaic power plant grid-connected stability control system according to an embodiment of the present invention.

[0101] This invention provides a stabilization device for a photovoltaic power plant grid-connected stability control system, comprising:

[0102] Photovoltaic array partitioning module 1 is used to determine the photovoltaic arrays corresponding to each connected inverter interface controller, divide all photovoltaic arrays into switching groups and modulation groups, and divide all photovoltaic arrays in the modulation group into multiple sub-photovoltaic array groups.

[0103] The controllable capacity reporting module 2 is used to receive the active power of the photovoltaic array sent by the interface controllers of each connected inverter, determine the controllable capacity information based on the active power, and send it to the upper-level stability control system; the controllable capacity information includes the maximum switchable capacity of the photovoltaic array corresponding to the switching unit and the maximum modulated capacity of the photovoltaic array corresponding to each sub-photovoltaic array group.

[0104] The stability control command receiving module 3 is used to receive the stability control command sent by the upper-level stability control system when a fault occurs in the corresponding power system; the stability control command is generated by the upper-level stability control system based on the controllable capacity information and the instability condition corresponding to the fault in the corresponding power system;

[0105] The stability control command execution module 4 is used to send a photovoltaic array cutoff command to the inverter interface controller corresponding to the cutoff group when the stability control command is a cutoff command, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; when the stability control command is a modulation command, it sends a stability control power fast adjustment command to the corresponding inverter interface controller in rounds according to the order of each of the sub-photovoltaic array groups in the modulation group, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array.

[0106] In one feasible implementation, the cut-off command includes the required cut-off capacity, and the stability control command execution module 4 includes:

[0107] The selection unit is used to select a photovoltaic array from the cut-off unit and add it to the set of photovoltaic arrays to be cut, until the total modulable capacity of the photovoltaic arrays in the set of photovoltaic arrays to be cut reaches the required cut-off capacity.

[0108] The first sending unit is used to send a command to cut off the photovoltaic array to the inverter interface controller corresponding to each of the photovoltaic arrays that need to be cut off.

[0109] In one feasible approach, the photovoltaic array in the switching unit is configured with a switching priority, and the selection unit is specifically used for:

[0110] Photovoltaic arrays are selected from the switching groups in descending order of priority and added to the set of photovoltaic arrays to be switched.

[0111] In one feasible manner, the photovoltaic array partitioning module 1 includes:

[0112] An acquisition unit is used to acquire the modulation priority of all photovoltaic arrays in the modulation group;

[0113] The sorting unit is used to sort all the photovoltaic arrays in the modulation group in descending order of modulation priority to obtain a sorted photovoltaic array sequence.

[0114] A partitioning unit is used to divide the sorted photovoltaic array sequence into multiple sub-photovoltaic array groups.

[0115] In one feasible implementation, the modulation instruction includes the modulation capacity to be modulated, and the stabilization instruction execution module 4 includes:

[0116] The second transmitting unit is used to send a power stabilization fast adjustment command to the inverter interface controller corresponding to the first group of sub-photovoltaic arrays arranged in the modulation group.

[0117] The calculation and update unit is used to calculate the power regulation amount of the current cycle based on the actual power regulation amount fed back by the corresponding inverter interface controller, and update the cumulative power regulation amount based on the calculated power regulation amount of the current cycle.

[0118] The loop execution unit is used to determine whether the new cumulative power adjustment amount has reached the required modulation capacity; if yes, it determines that the modulation instruction has been completed and ends the current stabilization power fast adjustment; if no, it sends the stabilization power fast adjustment command to the inverter interface controller corresponding to the next group of sub-photovoltaic arrays in the modulation group and returns to the previous step.

[0119] In one feasible implementation, the stabilization device is equipped with a control word, such as... Figure 5 As shown, in Figure 4 Based on the method shown, the stabilization device further includes:

[0120] The local execution module 5 is used to, when triggered to execute the local stability control strategy, send a photovoltaic array cut-off command to the inverter interface controller corresponding to the cut-off unit if the current control word is set to 1, so that the corresponding inverter interface controller controls the tripping of the corresponding grid connection point switch; if the current control word is set to 0, send a power stabilization fast adjustment command to the corresponding inverter interface controller in rounds according to the order of each of the sub-photovoltaic array groups in the modulation group, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array; the execution of the local stability control strategy includes executing high-frequency, low-frequency disconnection or fault disconnection actions.

[0121] This invention also provides a stabilization control device for a photovoltaic power plant grid-connected stability control system. The stabilization control device connects to an upstream stabilization control system and an inverter interface controller. Each inverter interface controller is connected to a corresponding photovoltaic array. The stabilization control device includes:

[0122] A memory is used to store instructions; wherein the instructions are used to implement the control method of the photovoltaic power plant grid-connected stability control system as described in any of the above embodiments;

[0123] A processor for executing instructions in the memory.

[0124] The present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, which, when executed by a processor, implements the control method of the photovoltaic power plant grid-connected stability control system as described in any of the above embodiments.

[0125] The present invention also provides a photovoltaic power plant grid-connected stability control system, characterized in that it includes an upper-level stability control system, an inverter interface controller, and a stability control device of the photovoltaic power plant grid-connected stability control system as described in any of the above embodiments.

[0126] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the above-described stabilization devices, modules, and units can be referred to the corresponding processes in the foregoing method embodiments, and the specific beneficial effects of the above-described stabilization devices, modules, and units can be referred to the corresponding beneficial effects in the foregoing method embodiments, and will not be repeated here.

[0127] In the several embodiments provided in this application, it should be understood that the disclosed stabilization device and control method can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0128] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0129] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0130] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0131] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method of a grid-connected stable control system of a photovoltaic power station, applied to a stable control device, the stable control device being connected to a superior stable control system and an inverter interface controller, each of the inverter interface controllers being connected to a corresponding photovoltaic array, characterized in that, The method comprises: determining the photovoltaic arrays corresponding to each connected inverter interface controller, dividing all the photovoltaic arrays into a tripping group and a modulation group, and dividing all the photovoltaic arrays in the modulation group into a plurality of sub-photovoltaic array groups; receiving active power of the photovoltaic arrays on each connected inverter interface controller, determining controllable capacity information according to the active power, and sending the controllable capacity information to a superior stability control system; the controllable capacity information comprises maximum controllable capacity of the photovoltaic arrays corresponding to the tripping group and maximum controllable capacity of the photovoltaic arrays corresponding to each sub-photovoltaic array group; receiving a stability control instruction sent by the superior stability control system when a corresponding power system fails; the stability control instruction is generated by the superior stability control system according to the controllable capacity information and a corresponding instability working condition when the corresponding power system fails; the instability working condition comprises power angle instability, frequency instability, voltage instability, and line overload; if the stability control instruction is a tripping instruction, sending a photovoltaic array tripping command to the inverter interface controller corresponding to the tripping group according to the tripping instruction, so that the corresponding inverter interface controller controls a corresponding grid-connected point switch to be tripped; if the stability control instruction is a modulation instruction, sending a stability control power quick modulation command to the inverter interface controller corresponding to each sub-photovoltaic array group in turn according to the order of the sub-photovoltaic array groups in the modulation group, so that the corresponding inverter interface controller modulates the power of the corresponding photovoltaic array; the tripping instruction comprises a required tripping capacity, and the sending of the photovoltaic array tripping command to the inverter interface controller corresponding to the tripping group according to the tripping instruction comprises: selecting a photovoltaic array from the tripping group and adding it to a required tripping photovoltaic array set until the sum of the modulatable capacities of the photovoltaic arrays in the required tripping photovoltaic array set reaches the required tripping capacity; sending a photovoltaic array tripping command to the inverter interface controller corresponding to each required tripping photovoltaic array; the photovoltaic arrays in the tripping group are configured with tripping priorities, and the selecting of the photovoltaic array from the tripping group and the adding of it to the required tripping photovoltaic array set comprise: selecting the photovoltaic arrays from the tripping group in turn and adding them to the required tripping photovoltaic array set in the order from high to low of the tripping priorities; the modulation instruction comprises a required modulation capacity, and the sending of the stability control power quick modulation command to the inverter interface controller corresponding to each sub-photovoltaic array group in turn according to the order of the sub-photovoltaic array groups in the modulation group comprises: sending a stability control power quick modulation command to the inverter interface controller corresponding to the first group of sub-photovoltaic array groups arranged in the modulation group; calculating a power adjustment amount of a current round according to an actual power adjustment amount fed back by each corresponding inverter interface controller, and updating a cumulative power adjustment amount according to the calculated power adjustment amount of the current round; determining whether the updated cumulative power adjustment amount reaches the required modulation capacity; if yes, determining that the modulation instruction is completed, and ending the current stability control power quick modulation; if no, sending a stability control power quick modulation command to the inverter interface controller corresponding to the next group of sub-photovoltaic array groups arranged in the modulation group, and returning to the previous step.

2. The control method of the photovoltaic power plant grid-connected stabilization control system according to claim 1, characterized by, the dividing of all the photovoltaic arrays in the modulation group into a plurality of sub-photovoltaic array groups comprises: acquire modulation priorities of all photovoltaic arrays in the modulation group; sort all photovoltaic arrays in the modulation group in order of modulation priority from high to low to obtain a sorted photovoltaic array sequence; divide the sorted photovoltaic array sequence into multiple sub-photovoltaic array groups.

3. The control method of the photovoltaic power plant grid-connected stabilization control system according to claim 1, characterized by, The stable control device is configured with a control word, and the method further comprises: When the on-site stable control strategy is triggered to be executed, if the current control word is set to 1, a photovoltaic array tripping command is sent to the corresponding inverter interface controller of the tripping group, so that the corresponding inverter interface controller controls the corresponding grid point switch to be tripped; if the current control word is set to 0, according to the order of each sub-photovoltaic array group in the modulation group, a stable control power fast regulation command is sent to the corresponding inverter interface controller in turns, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array; the execution of the on-site stable control strategy includes the actions of high-cycle, low-frequency tripping or fault tripping.

4. A stability control device of a grid-connected stability control system of a photovoltaic power plant, the stability control device being connected to a higher-level stability control system and an inverter interface controller, each of the inverter interface controllers being connected to a corresponding photovoltaic array, characterized in that, The stable control device comprises: a memory for storing instructions; wherein the instructions are used to implement the control method of the photovoltaic power station grid connection stability control system according to any one of claims 1-3; a processor for executing the instructions in the memory.

5. A computer readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the control method of the photovoltaic power station grid connection stability control system according to any one of claims 1-3.

6. A stability control device of a grid-connected stability control system of a photovoltaic power plant, the stability control device being connected to a higher-level stability control system and an inverter interface controller, each of the inverter interface controllers being connected to a corresponding photovoltaic array, characterized in that, The stable control device comprises: a photovoltaic array division module for determining the corresponding photovoltaic array of each connected inverter interface controller, dividing all photovoltaic arrays into a tripping group and a modulation group, and dividing all photovoltaic arrays in the modulation group into multiple sub-photovoltaic array groups; a controllable capacity reporting module for receiving the active power of the photovoltaic array sent by each connected inverter interface controller, determining controllable capacity information according to the active power, and sending the controllable capacity information to the upper stable control system; the controllable capacity information includes the maximum trippable capacity of the photovoltaic array corresponding to the tripping group and the maximum modulatable capacity of the photovoltaic array corresponding to each sub-photovoltaic array group; a stable control instruction receiving module for receiving the stable control instruction sent by the upper stable control system when the corresponding power system fails; the stable control instruction is generated by the upper stable control system according to the controllable capacity information and the corresponding instability working condition when the corresponding power system fails; the instability working condition includes power angle instability, frequency instability, voltage instability, and line overload; a stable control instruction execution module for, when the stable control instruction is a tripping instruction, sending a photovoltaic array tripping command to the corresponding inverter interface controller of the tripping group according to the tripping instruction, so that the corresponding inverter interface controller controls the corresponding grid point switch to be tripped; when the stable control instruction is a modulation instruction, a stable control power fast regulation command is sent to the corresponding inverter interface controller in turns according to the order of each sub-photovoltaic array group in the modulation group, so that the corresponding inverter interface controller performs power modulation on the corresponding photovoltaic array; The cut-off instruction includes a required cut-off capacity, and the sending of the cut-off photovoltaic array command to the corresponding inverter interface controller according to the cut-off instruction includes: selecting photovoltaic arrays from the cut-off group and adding them to the required cut-off photovoltaic array set until the total modulatable capacity of the photovoltaic arrays in the required cut-off photovoltaic array set reaches the required cut-off capacity; sending a cut-off photovoltaic array command to the corresponding inverter interface controller of each required cut-off photovoltaic array; The photovoltaic arrays in the cut-off group are configured with a cut-off priority, and the selecting of photovoltaic arrays from the cut-off group and adding them to the required cut-off photovoltaic array set includes: selecting photovoltaic arrays from the cut-off group and adding them to the required cut-off photovoltaic array set in order from high to low according to the cut-off priority; The modulation instruction includes a required modulation capacity, and the sending of the fast regulating command of the stable control power according to the order of each sub-photovoltaic array group in the modulation group includes: sending a fast regulating command of the stable control power to the inverter interface controller corresponding to the first sub-photovoltaic array group arranged in the modulation group; calculating the power adjustment amount of the current round according to the actual power adjustment amount fed back by each corresponding inverter interface controller and updating the cumulative power adjustment amount according to the calculated power adjustment amount of the current round; determining whether the updated cumulative power adjustment amount reaches the required modulation capacity; if yes, determining that the modulation instruction is completed and ending the fast regulating command of the stable control power; if no, sending a fast regulating command of the stable control power to the inverter interface controller corresponding to the next sub-photovoltaic array group arranged in the modulation group and returning to the previous step.

7. A grid-connected stable control system for a photovoltaic power station, characterized by, The stable control device includes a superordinate stable control system, an inverter interface controller, and a photovoltaic power station grid-connected stable control system as claimed in claim 6.

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