Inverter control method and system, power system and inverter scheduling method

Abstract

The invention relates to the technical field of power control, and provides an inverter control method and system, a power system and an inverter scheduling method.The method comprises the following steps executed by a circuit breaker: obtaining a preset change curve sent by a master station; determining target power according to the current time and a preset change curve; and performing output control on the plurality of inverters according to the target power. In the embodiment of the invention, the main station can send the preset change curve representing power and time mapping of the power demand in a future period of time to the circuit breaker, so that the subsequent circuit breaker can determine the corresponding target power according to the current time and the preset change curve, and then output control is carried out on the plurality of inverters according to the target power. According to the invention, the circuit breaker only needs to communicate with the master station once to realize output control of the plurality of inverters for a period of time, control transmission between the master station and the inverters does not need to be frequently carried out, the communication is simple, the situation of command loss is not easy to occur, and finally the control reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power control, and in particular to an inverter control method, system, power system and inverter scheduling method. Background Art

[0002] The power system in photovoltaic grid-connected power generation usually includes multiple inverters, and the purpose of photovoltaic grid-connected power generation is achieved by controlling the power output of multiple inverters.

[0003] The traditional control method has poor effect, which leads to errors in the control of the inverter. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an inverter control method, system, power system and inverter scheduling method.

[0005] In a first aspect, in one embodiment, the present invention provides an inverter control method, which is applied to an inverter control system, the inverter control system including a master station, a circuit breaker electrically connected to the master station and respectively electrically connected to a plurality of inverters; the inverter control method includes the following steps performed by the circuit breaker: Obtaining a preset change curve of power and time mapping sent by the master station; Determine the target power according to the current time and the preset change curve; According to the target power, the output of the multiple inverters is controlled so that the total power output by the multiple inverters can meet the target power.

[0006] In one embodiment, determining the target power according to the current time and the preset change curve includes: According to the current time, match the corresponding sample time in the preset change curve; The sample power corresponding to the sample time in the preset change curve is determined as the target power.

[0007] In one embodiment, output control of multiple inverters is performed according to target power, including: Get the current total power of multiple inverters; Determine the power adjustment strategies of multiple inverters according to the target power and the current total power; the power adjustment strategy includes the power adjustment direction and the power adjustment size; The output of multiple inverters is controlled according to the power adjustment strategy.

[0008] In one embodiment, output control of multiple inverters is performed according to a power adjustment strategy, including: If the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, determining an inverter whose switch state is in an off state among the multiple inverters; According to the power adjustment size, determining at least one inverter whose switch state is an off state as a first target inverter; The switch state of the first target inverter is controlled to be an on state, and the output of the first target inverter is controlled so that the total power output by the first target inverter can meet the power represented by the power adjustment size.

[0009] In one embodiment, if the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, determining the inverters whose switch states are in the off state among the multiple inverters includes: If the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, determining an inverter whose switch state is in an on state among the multiple inverters; Determine the remaining power of each inverter whose switch state is an on state according to the first preset power; If the sum of the remaining powers of the inverters whose switch states are turned on cannot satisfy the power represented by the power adjustment size, an inverter whose switch state is turned off among the multiple inverters is determined.

[0010] In one embodiment, after the step of determining the remaining power of each inverter whose switch state is the on state according to the first preset power, the inverter control method further includes: If the sum of the remaining powers of the inverters whose switch states are turned on can satisfy the power represented by the power adjustment size, then at least one inverter whose switch state is turned on is determined as the second target inverter according to the power adjustment size; The output of the second target inverter is controlled so that the total power increased by the second target inverter can meet the power represented by the power adjustment size.

[0011] In one embodiment, according to the power adjustment size, determining at least one inverter whose switch state is in the off state as the first target inverter includes: Determine a first conversion time for each inverter whose switch state is the off state to be converted to the off state; Determining, according to the first conversion time, a start priority of each inverter whose switch state is the off state; According to the power adjustment size and the start priority of each inverter whose switch state is the off state, at least one inverter whose switch state is the off state is determined as a first target inverter; The inverter with an earlier first conversion time has a higher start-up priority.

[0012] In one embodiment, output control of multiple inverters is performed according to a power adjustment strategy, including: If the power adjustment direction indicates that the total power of the multiple inverters needs to be reduced, at least one inverter whose switch state is turned on is determined as a third target inverter according to the power adjustment size; The switch state of the third target inverter is controlled to be an off state, so that the total power interrupted by the third target inverter can meet the power represented by the power adjustment size.

[0013] In one embodiment, if the power adjustment direction indicates that the total power of multiple inverters needs to be reduced, at least one inverter whose switch state is turned on is determined as a third target inverter according to the power adjustment size, including: If the power adjustment direction indicates that the total power of the plurality of inverters needs to be reduced, then determining the excess power of each inverter whose switch state is the on state according to the second preset power; If the sum of excess powers of the inverters whose switch states are turned on cannot satisfy the power represented by the power adjustment magnitude, at least one inverter whose switch state is turned on is determined as the third target inverter.

[0014] In one embodiment, after the step of determining the excess power of each inverter whose switch state is an on state according to the second preset power, the inverter control method further includes: If the sum of excess powers of the inverters whose switch states are turned on can satisfy the power represented by the power adjustment size, at least one inverter whose switch state is turned on is determined as a fourth target inverter; The output of the fourth target inverter is controlled so that the total power reduced by the fourth target inverter can meet the power represented by the power adjustment size.

[0015] In one embodiment, according to the power adjustment size, determining at least one inverter whose switch state is in an on state as a third target inverter includes: Determine a second conversion time for each inverter whose switch state is the on state to be converted to the on state; Determining, according to the second conversion time, a shutdown priority of each inverter whose switch state is an on state; At least one inverter whose switch state is in the on state is determined as a third target inverter according to the power adjustment size and the shutdown priority of each inverter whose switch state is in the on state.

[0016] In a second aspect, in one embodiment, the present invention provides an inverter control system, the inverter control system comprising a master station, a circuit breaker electrically connected to the master station and used to be electrically connected to multiple inverters respectively; the circuit breaker is used to execute the inverter control method in any of the above embodiments.

[0017] In one embodiment, the inverter system further includes an intermediate device, the intermediate device is electrically connected to the master station, and the intermediate device is electrically connected to the circuit breaker via a power line; The intermediate device is used to communicate with the circuit breaker based on the power line and through the carrier communication method.

[0018] In a third aspect, in one embodiment, the present invention provides a power system, comprising a plurality of inverters and an inverter control system according to any one of the above embodiments.

[0019] In one embodiment, the circuit breaker comprises a first digital input port and a first digital output port, and each inverter comprises a second digital input port and a second digital output port, respectively; The first digital output port is electrically connected to each second digital input port respectively, and the first digital input port is electrically connected to each second digital output port respectively.

[0020] In a fourth aspect, in one embodiment, the present invention provides an inverter scheduling method, which is applied to the power system in the above embodiment; the inverter scheduling method includes: The circuit breaker sends a dispatch instruction to each second digital input port through the first digital output port; Each inverter completes the corresponding scheduling operation according to the received scheduling instruction, and sends a feedback instruction to the first digital input port through the second digital output port; The circuit breaker determines the completion status of the corresponding scheduling operation based on each feedback instruction received.

[0021] In one embodiment, the scheduling instruction includes a dry contact opening instruction representing the control of turning on the inverter, a dry contact closing instruction representing the control of turning off the inverter, or a pulse signal instruction representing the control of the output power of the inverter.

[0022] In one embodiment, each inverter completes a corresponding scheduling operation according to the received scheduling instruction, and sends a feedback instruction to the first digital input port through the second digital output port, including: For each inverter, If the inverter successfully completes the corresponding scheduling operation, it sends a dry contact closing instruction indicating successful completion to the first digital input port through the corresponding second digital output port; If the inverter fails to successfully complete the corresponding scheduling operation, the inverter sends a dry contact port instruction indicating unsuccessful completion to the first digital input port through the corresponding second digital output port; The circuit breaker determines the completion status of the corresponding scheduling operation based on each feedback instruction received, including: For each feedback command, If the feedback instruction is a dry contact closing instruction, a completion status indicating successful completion is obtained; If the feedback instruction is a dry contact disconnection instruction, a completion status indicating unsuccessful completion is obtained.

[0023] Through the inverter control method, system, power system and inverter scheduling method, the master station can send a preset change curve of power and time mapping representing the power demand for a period of time in the future to the circuit breaker, so that the subsequent circuit breaker can determine the corresponding target power according to the current time and the preset change curve, and then control the output of multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to realize the output control of multiple inverters for a period of time, without the need for frequent control transmission between the master station and the inverter, the communication is simple, and the command loss is not easy to occur, which ultimately improves the reliability of control. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments 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 work.

[0025] Figure 1 A schematic diagram of the structure of a power system in one embodiment of the present invention; Figure 2 A schematic diagram of a preset change curve in one embodiment of the present invention; Figure 3 A schematic diagram of the connection mode of the circuit breaker with the master station and the inverter in one embodiment of the present invention; Figure 4 The figure is a flow chart of an inverter scheduling method in one embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In the present application, the word "exemplary" is used to mean "used as an example, illustration or description". Any embodiment described as "exemplary" in the present application is not necessarily interpreted as being more preferred or more advantageous than other embodiments. In order to enable any person skilled in the art to implement and use the present invention, the following description is given. In the following description, details are listed for the purpose of explanation. It should be understood that those of ordinary skill in the art will recognize that the present invention can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid unnecessary details that make the description of the present invention obscure. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in this application.

[0028] First, as Figure 1 As shown, in one embodiment, the present invention provides an inverter control method, and the inverter control method is applied to an inverter control system.

[0029] like Figure 1 As shown, the inverter control system includes a master station, a circuit breaker electrically connected to the master station and used to be electrically connected to a plurality of inverters respectively.

[0030] The master station is responsible for the overall control of the power grid. The circuit breaker is set between the master station and the inverter to control the transmission. The inverter can invert the power generated by photovoltaics into AC power to output to the power grid. Figure 1 In the embodiment, setting three inverters is only an example, and in other embodiments, a greater or lesser number may be included.

[0031] The inverter control method includes the following steps performed by the circuit breaker: Get the preset change curve of power and time mapping sent by the master station.

[0032] The master station may obtain the preset change curve based on historical data.

[0033] The historical data may include historical power, historical power consumption, and specific moments corresponding to a certain time period. For example, the preset change curve may be a change curve of power and time mapping within 24 hours. The master station may determine the power at multiple moments in 24 hours, and then obtain the preset change curve by curve fitting.

[0034] As an example, the preset change curve obtained by the master station fitting is as follows: Figure 2 As shown, the preset change curve is in a corresponding vertical coordinate system, the horizontal axis of the vertical coordinate system is time t (unit is h), and the vertical axis of the vertical coordinate system is power P (unit is w).

[0035] Determine the target power based on the current time and the preset change curve.

[0036] Among them, the above steps have mentioned that the master station can pre-plan the power demand for the next 24 hours. When the circuit breaker obtains the preset change curve, it can determine the target power corresponding to the current time by matching the preset change curve according to the current time.

[0037] According to the target power, the output of the multiple inverters is controlled so that the total power output by the multiple inverters can meet the target power.

[0038] Among them, it should be noted that before the output of multiple inverters is controlled, the multiple inverters themselves have corresponding power outputs. The total power output of multiple inverters can be understood as the current total power, which is controlled by the historical target power obtained by the last circuit breaker. The circuit breaker needs to perform specific power control based on the relationship between the currently determined target power and the current total power being executed by multiple inverters. For example, if the target power is greater than the current total power, it is necessary to control multiple inverters to increase the total power. If the target power is equal to the current total power, it is necessary to control multiple inverters to maintain the total power. If the target power is less than the current total power, it is necessary to control multiple inverters to reduce the total power.

[0039] Among them, whether controlling multiple inverters to increase the total power, maintain the total power or reduce the total power, it is necessary to ensure that the total power output by the multiple inverters can meet the target power.

[0040] Through the above inverter control method, the master station can send a preset change curve of power and time mapping representing the power demand for a period of time in the future to the circuit breaker, so that the subsequent circuit breaker can determine the corresponding target power according to the current time and the preset change curve, and then control the output of multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to realize the output control of multiple inverters for a period of time, without the need for frequent control transmission between the master station and the inverter, the communication is simple, and the command loss is not easy to occur, which ultimately improves the reliability of control.

[0041] In one embodiment, determining the target power according to the current time and the preset change curve includes: According to the current time, match the corresponding sample time in the preset change curve; The sample power corresponding to the sample time in the preset change curve is determined as the target power.

[0042] Among them, the above embodiment has mentioned that after determining the current time, the corresponding sample time can be matched in the preset change curve by matching. However, the current time may be a real-time value and cannot be directly matched with the time listed on the horizontal axis of the preset change curve. In this case, relevant processing needs to be performed on the current time.

[0043] Specifically, if the current time is 15:00 on January 1, and the preset change curve sent by the master station is used to represent the power demand from 09:00 on January 1 to 08:00 on January 2, then in the preset change curve, when the horizontal axis is 1h, the corresponding real-time value is 09:00 on January 1, and when the horizontal axis is 2h, the corresponding real-time value is 10:00 on January 1. Therefore, if the current time is 15:00 on January 1, the sample time matching it in the preset change curve is 7h, and finally the sample power corresponding to the sample time 7h can be determined as the target power.

[0044] Of course, in other embodiments, when the current time is expressed in a different manner, the corresponding target power can also be determined based on other manners according to the preset change curve and the current time.

[0045] In one embodiment, output control of multiple inverters is performed according to target power, including: Get the current total power of multiple inverters; Determine the power adjustment strategy of multiple inverters according to the target power and the current total power; The output of multiple inverters is controlled according to the power adjustment strategy.

[0046] Among them, the above-mentioned embodiment has mentioned that when controlling according to the target power, the specific power control can be further performed according to the current total power of multiple inverters, so as to perform specific power control according to the magnitude relationship between the target power and the current total power. In this embodiment, after obtaining the current total power of multiple inverters, the corresponding power adjustment strategy can be determined according to the target power and the current total power. Since the power adjustment strategy represents how to adjust the power of multiple inverters, the output of multiple inverters can be directly controlled according to the power adjustment strategy to adjust the power output thereof.

[0047] Specifically, the power adjustment strategy includes a power adjustment direction and a power adjustment size. The power adjustment direction is used to indicate that multiple inverters need to increase the total power, maintain the total power, or reduce the total power, and the power adjustment size is used to indicate the power change amount of multiple inverters. For example, when the power adjustment direction is used to indicate that multiple inverters need to increase the total power, the power adjustment size is specifically used to indicate the amount of power that needs to be increased. For example, when the power adjustment direction is used to indicate that multiple inverters need to reduce the total power, the power adjustment size is specifically used to indicate the amount of power that needs to be reduced.

[0048] In one embodiment, output control of multiple inverters is performed according to a power adjustment strategy, including: If the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, an inverter whose switch state is in the off state is determined among the multiple inverters.

[0049] When the total power of multiple inverters needs to be increased, if there are inverters whose switch state is off among the multiple inverters, it can be considered to turn on these inverters to bear the increased total power.

[0050] According to the power adjustment size, at least one inverter whose switch state is the off state is determined as the first target inverter.

[0051] Among them, when the power adjustment direction is used to indicate that multiple inverters need to increase the total power, the power adjustment size is specifically used to indicate the amount of power that needs to be increased, so that according to the power adjustment size, it can be determined how many inverters with switch states in the closed state need to be turned on to meet the demand, and the inverter that needs to be turned on is determined as the first target inverter.

[0052] The switch state of the first target inverter is controlled to be an on state, and the output of the first target inverter is controlled so that the total power output by the first target inverter can meet the power represented by the power adjustment size.

[0053] Among them, the output power of each first target inverter is adjustable. Therefore, after the switching state of the first target inverter is converted to the on state, the output of the first target inverter needs to be further controlled to distribute the power output by each first target inverter according to the power adjustment size, and finally ensure that the total power output by the first target inverter can meet the power represented by the power adjustment size.

[0054] In one embodiment, if the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, determining the inverters whose switch states are in the off state among the multiple inverters includes: If the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, an inverter whose switch state is in an on state among the multiple inverters is determined.

[0055] Among them, the above-mentioned embodiment has mentioned that when the total power needs to be increased, it is possible to consider directly turning on the inverter whose switch state is in the off state. However, in this embodiment, the working efficiency of the inverter can be further considered. It is possible to consider using an inverter whose switch state is in the on state but whose working efficiency is lower due to lower output power to bear the increased total power.

[0056] According to the first preset power, the remaining power of each inverter whose switch state is the on state is determined.

[0057] The first preset power can be used to characterize the working efficiency of the inverter. When the output power of the inverter is lower than the first preset power, it can be considered that the working efficiency of the inverter is low. Therefore, the remaining power corresponding to when the output power of each inverter whose switch state is the on state can be increased to the first preset power can be further determined according to the first preset power.

[0058] If the sum of the remaining powers of the inverters whose switch states are turned on cannot satisfy the power represented by the power adjustment size, an inverter whose switch state is turned off among the multiple inverters is determined.

[0059] If the sum of the determined remaining powers cannot satisfy the power represented by the power adjustment size, it means that the inverter currently turned on cannot fully bear the increased total power by only increasing the output power to the first preset power. In view of this situation, it is possible to further consider turning on an inverter whose switch state is turned off.

[0060] It should be noted that in this embodiment, if the sum of the determined remaining powers cannot meet the power represented by the power adjustment size, in addition to considering turning on the inverter whose switch state is turned off to fully bear the increased total power; the inverter whose switch state is turned on can also bear part of the increased total power based on improved work efficiency, and turn on fewer inverters whose switch state is turned off to bear the remaining part of the increased total power.

[0061] In one embodiment, after the step of determining the remaining power of each inverter whose switch state is the on state according to the first preset power, the inverter control method further includes: If the sum of the remaining powers of the inverters whose switch states are turned on can satisfy the power represented by the power adjustment size, at least one inverter whose switch state is turned on is determined as the second target inverter according to the power adjustment size.

[0062] If the determined sum of the remaining powers can satisfy the power represented by the power adjustment size, it means that the inverter currently turned on can fully bear the increased total power only by increasing the output power to the first preset power. In this case, at least one inverter whose switch state is turned on can be directly determined as the second target inverter according to the power adjustment size and the remaining power of each inverter.

[0063] The output of the second target inverter is controlled so that the total power increased by the second target inverter can meet the power represented by the power adjustment size.

[0064] Among them, since the second target inverter was already in the on state and had a certain power output before this control, in this control, the main thing is to increase the power output of the second target inverter, and finally ensure that the total power increased by the second target inverter can meet the power represented by the power adjustment size.

[0065] In one embodiment, according to the power adjustment size, determining at least one inverter whose switch state is in the off state as the first target inverter includes: A first switching time for each inverter whose switch state is the off state to switch to the off state is determined.

[0066] Each inverter whose switch state is the off state is converted from the on state, and the time when the conversion occurs is the first conversion time.

[0067] According to the first conversion time, a start priority of each inverter whose switch state is the off state is determined.

[0068] Among them, overusing a certain inverter will reduce the life of the inverter, and thus reduce the life of the entire power system. Therefore, in order to make the use of each inverter more balanced, the inverter that enters the shutdown state first can be turned on first. To achieve this purpose, after determining the first conversion time of each inverter, the corresponding opening priority can be determined according to the first conversion time, and the inverter with a higher opening priority is turned on first.

[0069] In view of the purpose of balancing, it can be determined that the inverter with an earlier first conversion time has a higher start priority.

[0070] At least one inverter whose switch state is in the off state is determined as a first target inverter according to the power adjustment size and the start priority of each inverter whose switch state is in the off state.

[0071] Among them, if one inverter needs to be turned on, the inverter with the highest priority will be turned on. Similarly, if two inverters need to be turned on, the two inverters with the highest priority will be turned on.

[0072] In one embodiment, output control of multiple inverters is performed according to a power adjustment strategy, including: If the power adjustment direction indicates that the total power of the plurality of inverters needs to be reduced, then at least one inverter whose switch state is an on state is determined as a third target inverter according to the power adjustment size.

[0073] Among them, when multiple inverters need to reduce the total power, it is possible to consider directly shutting down some inverters. When the power adjustment direction is used to indicate that multiple inverters need to reduce the total power, the power adjustment size is specifically used to indicate the amount of power that needs to be reduced, so that according to the power adjustment size, it can be determined how many inverters with the switch state in the on state need to be shut down to meet the demand, and the inverter that needs to be shut down is determined as the third target inverter.

[0074] The switch state of the third target inverter is controlled to be an off state, so that the total power interrupted by the third target inverter can meet the power represented by the power adjustment size.

[0075] Compared with turning on the inverter, turning off the inverter can directly interrupt the power output by the inverter, thereby eliminating the need to further control the output of the inverter, and ultimately ensuring that the total power interrupted by the third target inverter can meet the power represented by the power adjustment size.

[0076] In one embodiment, if the power adjustment direction indicates that the total power of multiple inverters needs to be reduced, at least one inverter whose switch state is turned on is determined as a third target inverter according to the power adjustment size, including: If the power adjustment direction indicates that the total power of the plurality of inverters needs to be reduced, then the excess power of each inverter whose switch state is the on state is determined according to the second preset power.

[0077] Among them, the above-mentioned embodiment has mentioned that when the total power needs to be reduced, it is possible to consider directly shutting down the inverter whose switch state is on. However, in this embodiment, the load condition of the inverter can be further considered. An inverter whose switch state is on but whose load condition has certain hidden dangers due to the high output power can be considered to bear the reduced total power.

[0078] The second preset power can be used to characterize the load condition of the inverter. When the output power of the inverter is higher than the second preset power, it can be considered that the load condition of the inverter has certain safety hazards. Therefore, the output power of each inverter in the on state can be further determined according to the second preset power to reduce the excess power corresponding to the second preset power.

[0079] If the sum of excess powers of the inverters whose switch states are turned on cannot satisfy the power represented by the power adjustment magnitude, at least one inverter whose switch state is turned on is determined as the third target inverter.

[0080] If the sum of the excess powers determined cannot satisfy the power represented by the power adjustment size, it means that the inverter currently turned on cannot fully bear the reduced total power by only reducing the output power to the second preset power. In view of this situation, it is further considered to turn off the inverter whose switch state is turned on.

[0081] It should be noted that in this embodiment, if the sum of the excess powers determined cannot meet the power represented by the power adjustment size, in addition to considering turning off the inverter whose switch state is on to fully bear the increased total power; the inverter whose switch state is on can also bear the reduced part of the total power based on the load condition that reduces the safety hazard, and turn off the inverter with fewer switch states on to bear the remaining reduced total power.

[0082] In one embodiment, after the step of determining the excess power of each inverter whose switch state is an on state according to the second preset power, the inverter control method further includes: If the sum of excess powers of the inverters whose switch states are turned on can satisfy the power represented by the power adjustment size, at least one inverter whose switch state is turned on is determined as the fourth target inverter.

[0083] If the determined sum of excess power can satisfy the power represented by the power adjustment size, it means that the inverter currently turned on can fully bear the reduced total power only by reducing the output power to the second preset power. In this case, at least one inverter whose switch state is turned on can be directly determined as the fourth target inverter according to the power adjustment size and the excess power of each inverter.

[0084] The output of the fourth target inverter is controlled so that the total power reduced by the fourth target inverter can meet the power represented by the power adjustment size.

[0085] Among them, since the fourth target inverter was already in the on state and had a certain power output before this control, in this control, the main thing is to reduce the power output of the fourth target inverter, and finally ensure that the total power reduced by the fourth target inverter can meet the power represented by the power adjustment size.

[0086] In one embodiment, according to the power adjustment size, determining at least one inverter whose switch state is in an on state as a third target inverter includes: A second switching time for each inverter whose switch state is the on state to switch to the on state is determined.

[0087] Each inverter whose switch state is the on state is converted from the off state, and the time when the conversion occurs is the second conversion time.

[0088] According to the second conversion time, a shutdown priority of each inverter whose switch state is the on state is determined.

[0089] Among them, overusing a certain inverter will reduce the life of the inverter, and thus reduce the life of the entire power system. Therefore, in order to make the use of each inverter more balanced, the inverter that enters the open state first can be turned off first. To achieve this purpose, after determining the second conversion time of each inverter, the corresponding shutdown priority can be determined according to the second conversion time, and the inverter with a higher shutdown priority will be turned off first.

[0090] In view of the purpose of balancing, it can be determined that the inverter with an earlier second conversion time has a higher shutdown priority.

[0091] At least one inverter whose switch state is in the on state is determined as a third target inverter according to the power adjustment size and the shutdown priority of each inverter whose switch state is in the on state.

[0092] Among them, if one inverter needs to be shut down, the inverter with the highest shutdown priority will be shut down. Similarly, if two inverters need to be shut down, the two inverters with the highest shutdown priority will be shut down.

[0093] In combination with the above embodiments, the circuit breaker controls multiple inverters in a "first-in, first-out, cycle in sequence" control mode. For example, there are 10 inverters hanging under a circuit breaker somewhere, numbered 1-10. Assuming that the power provided by the preset change curve at 8 a.m. is 2000Kw, then inverters 1-4 are turned on in sequence at this time, and each outputs 40%, which can meet the needs; at 12 noon, the power provided by the preset change curve is 5000Kw, then inverters 5-8 are turned on in sequence at this time, and each outputs 60%, which can meet the needs; until 5 p.m., the power provided by the preset change curve is 200Kw, because the inverters turned on first are 1-4, according to the control principle, inverters 1-4 are turned off first. If the inverter needs to be turned on later, continue to turn on 9, 10, 1, 2 in sequence. If the inverter needs to be turned off later, inverters 5-8 that were turned on before will be turned off first.

[0094] Second, as Figure 1 As shown, in one embodiment, the present invention provides an inverter control system, which includes a master station, a circuit breaker electrically connected to the master station and used to be electrically connected to multiple inverters respectively; the circuit breaker is used to execute the inverter control method in any of the above embodiments.

[0095] Through the inverter control system, the master station can send a preset change curve of power and time mapping representing the power demand for a period of time in the future to the circuit breaker, so that the subsequent circuit breaker can determine the corresponding target power according to the current time and the preset change curve, and then control the output of multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to realize the output control of multiple inverters for a period of time, without the need for frequent control transmission between the master station and the inverter, the communication is simple, and the command loss is not easy to occur, which ultimately improves the reliability of control.

[0096] like Figure 3 As shown, in one embodiment, the inverter system also includes an intermediate device, which is electrically connected to the main station. The intermediate device is electrically connected to the circuit breaker through a power line. The circuit breaker is provided with an HPLC port and is electrically connected to the intermediate device through the HPLC port. The intermediate device is used to communicate with the circuit breaker based on the power line and through a carrier communication method.

[0097] Among them, intermediate equipment includes front-end machines, concentrators / fusion terminals, etc.

[0098] Thirdly, Figure 1 As shown, in one embodiment, the present invention provides a power system, including a plurality of inverters and the inverter control system in any one of the above embodiments.

[0099] Through the above-mentioned power system, the master station can send a preset change curve of power and time mapping representing the power demand for a period of time in the future to the circuit breaker, so that the subsequent circuit breaker can determine the corresponding target power according to the current time and the preset change curve, and then control the output of multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to realize the output control of multiple inverters for a period of time, without the need for frequent control transmission between the master station and the inverter, the communication is simple, and the command loss is not easy to occur, which ultimately improves the reliability of control.

[0100] like Figure 3 As shown, in one embodiment, the circuit breaker includes a first digital input port DI_1 and a first digital output port DO_1, and each inverter includes a second digital input port DI_2 and a second digital output port DO_2.

[0101] The first digital output port DO_1 is electrically connected to each second digital input port DI_2, and the first digital input port DI_1 is electrically connected to each second digital output port DO_2.

[0102] In addition to the DI / DO communication method, other communication methods can also be used between the circuit breaker and the inverter, such as 485 communication.

[0103] In a fourth aspect, in one embodiment, the present invention provides an inverter scheduling method, which is applied to the power system in the above embodiment; the inverter scheduling method includes: The circuit breaker sends a dispatch instruction to each second digital input port through the first digital output port; Each inverter completes the corresponding scheduling operation according to the received scheduling instruction, and sends a feedback instruction to the first digital input port through the second digital output port; The circuit breaker determines the completion status of the corresponding scheduling operation based on each feedback instruction received.

[0104] Among them, refer to Figure 3 When the circuit breaker controls the inverter to turn on or off, it outputs instructions to the second digital input port DI_2 of the inverter through its first digital output port DO_1. The feedback of the inverter outputs instructions to the first digital input port DI_1 of the circuit breaker through the second digital output port DO_2. The circuit breaker and the master station exchange data through the HPLC power line carrier communication method.

[0105] In one embodiment, the scheduling instruction includes a dry contact opening instruction representing the control of turning on the inverter, a dry contact closing instruction representing the control of turning off the inverter, or a pulse signal instruction representing the control of the output power of the inverter.

[0106] In one embodiment, each inverter completes a corresponding scheduling operation according to the received scheduling instruction, and sends a feedback instruction to the first digital input port through the second digital output port, including: For each inverter, If the inverter successfully completes the corresponding scheduling operation, it sends a dry contact closing instruction indicating successful completion to the first digital input port through the corresponding second digital output port; If the inverter fails to successfully complete the corresponding scheduling operation, the inverter sends a dry contact port instruction indicating unsuccessful completion to the first digital input port through the corresponding second digital output port; The circuit breaker determines the completion status of the corresponding scheduling operation based on each feedback instruction received, including: For each feedback command, If the feedback instruction is a dry contact closing instruction, a completion status indicating successful completion is obtained; If the feedback instruction is a dry contact disconnection instruction, a completion status indicating unsuccessful completion is obtained.

[0107] Based on the above embodiments, Figure 4 As shown, in the default state, multiple inverters are connected to the grid for output. When the master station needs to regulate the inverter, a dispatch instruction is sent to the circuit breaker through the power line carrier. If it is necessary to control the inverter to open / close, the first digital output port DO_1 of the circuit breaker outputs the dispatch instruction to the inverter. The closing instruction is a dry contact closure, and the opening instruction is a dry contact disconnection. If the output power of the inverter needs to be adjusted, the first digital output port DO_1 of the circuit breaker outputs a pulse signal of 1hZ to 100hZ to the inverter, and the pulse frequency corresponds to the percentage of the rated power of the photovoltaic grid. After completing a dispatch instruction, the inverter feeds back a feedback signal to the circuit breaker through the second digital output port DO_2. If the dispatch is successful, the inverter outputs a dry contact closure signal, and the duration is >3S; if the dispatch fails, the inverter outputs a dry contact disconnection signal.

[0108] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0109] The above is a detailed introduction to an inverter control method, system, power system and inverter scheduling method provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0110] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. An inverter control method, characterized in that: The inverter control method is applied to an inverter control system, the inverter control system includes a master station, a circuit breaker electrically connected to the master station and used to be electrically connected to a plurality of inverters respectively; the inverter control method includes the following steps performed by the circuit breaker: Obtaining a preset change curve of power and time mapping sent by the master station; Determine the target power according to the current time and the preset change curve; According to the target power, output of the plurality of inverters is controlled so that a total power output by the plurality of inverters can meet the target power.

2. The inverter control method according to claim 1, characterized in that: The determining the target power according to the current time and the preset change curve includes: According to the current time, matching a corresponding sample time in the preset change curve; The sample power corresponding to the sample time in the preset change curve is determined as the target power.

3. The inverter control method according to claim 1, characterized in that: The step of controlling the output of the plurality of inverters according to the target power comprises: Obtaining current total power of the multiple inverters; Determining a power adjustment strategy for the multiple inverters according to the target power and the current total power; the power adjustment strategy includes a power adjustment direction and a power adjustment magnitude; The output of the multiple inverters is controlled according to the power adjustment strategy.

4. The inverter control method according to claim 3, characterized in that: The step of controlling the output of the plurality of inverters according to the power adjustment strategy includes: If the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, determining an inverter whose switch state is in an off state among the multiple inverters; According to the power adjustment size, determining at least one inverter whose switch state is an off state as a first target inverter; The switch state of the first target inverter is controlled to be an on state, and the output of the first target inverter is controlled so that the total power output by the first target inverter can meet the power represented by the power adjustment size.

5. The inverter control method according to claim 4, characterized in that: If the power adjustment direction indicates that the plurality of inverters need to increase the total power, determining an inverter whose switch state is in a closed state among the plurality of inverters includes: If the power adjustment direction indicates that the total power of the multiple inverters needs to be increased, determining an inverter whose switch state is in an on state among the multiple inverters; Determine the remaining power of each inverter whose switch state is an on state according to the first preset power; If the sum of the remaining powers of the inverters whose switch states are turned on cannot satisfy the power represented by the power adjustment magnitude, an inverter whose switch state is turned off among the multiple inverters is determined.

6. The inverter control method according to claim 5, characterized in that: After the step of determining the remaining power of each inverter whose switch state is the on state according to the first preset power, the inverter control method further includes: If the sum of the remaining powers of the inverters whose switch states are turned on can satisfy the power represented by the power adjustment size, then according to the power adjustment size, at least one inverter whose switch state is turned on is determined as the second target inverter; The output of the second target inverter is controlled so that the total power increased by the second target inverter can meet the power represented by the power adjustment size.

7. The inverter control method according to claim 4, characterized in that: The step of adjusting the power size and determining at least one inverter whose switch state is an off state as a first target inverter includes: Determine a first conversion time for each inverter whose switch state is the off state to be converted to the off state; Determining, according to the first conversion time, a start priority of each inverter whose switch state is the off state; According to the power adjustment size and the start priority of each inverter whose switch state is the off state, determining at least one inverter whose switch state is the off state as a first target inverter; The inverter with an earlier first conversion time has a higher start-up priority.

8. The inverter control method according to claim 3, characterized in that: The step of controlling the output of the plurality of inverters according to the power adjustment strategy includes: If the power adjustment direction indicates that the plurality of inverters need to reduce total power, then according to the power adjustment magnitude, determining at least one inverter whose switch state is an on state as a third target inverter; The switch state of the third target inverter is controlled to be an off state, so that the total power interrupted by the third target inverter can meet the power represented by the power adjustment size.

9. The inverter control method according to claim 8, characterized in that: If the power adjustment direction indicates that the plurality of inverters need to reduce the total power, then according to the power adjustment size, at least one inverter whose switch state is in the on state is determined as a third target inverter, including: If the power adjustment direction indicates that the plurality of inverters need to reduce the total power, then determining the excess power of each inverter whose switch state is the on state according to the second preset power; If the sum of excess powers of the inverters whose switch states are turned on cannot satisfy the power represented by the power adjustment magnitude, at least one inverter whose switch state is turned on is determined as a third target inverter.

10. The inverter control method according to claim 9, characterized in that: After the step of determining the excess power of each inverter whose switch state is an on state according to the second preset power, the inverter control method further includes: If the sum of excess powers of the inverters whose switch states are turned on can satisfy the power represented by the power adjustment size, at least one inverter whose switch state is turned on is determined as a fourth target inverter; The output of the fourth target inverter is controlled so that the total power reduced by the fourth target inverter can meet the power represented by the power adjustment size.

11. The inverter control method according to claim 8, characterized in that: The step of adjusting the power size and determining at least one inverter whose switch state is an on state as a third target inverter includes: Determine a second conversion time for each inverter whose switch state is the on state to be converted to the on state; Determining, according to the second conversion time, a shutdown priority of each inverter whose switch state is an on state; At least one inverter whose switch state is in the on state is determined as a third target inverter according to the power adjustment size and the shutdown priority of each inverter whose switch state is in the on state.

12. An inverter control system, characterized in that: The inverter control system includes a master station, a circuit breaker electrically connected to the master station and used to be electrically connected to multiple inverters respectively; the circuit breaker is used to execute the inverter control method according to any one of claims 1 to 11.

13. The inverter control system according to claim 12, characterized in that: The inverter system further includes an intermediate device, the intermediate device being electrically connected to the master station, and the intermediate device being electrically connected to the circuit breaker via a power line; The intermediate device is used for communicating with the circuit breaker based on the power line and through a carrier communication method.

14. A power system, characterized in that: The invention comprises a plurality of inverters and the inverter control system according to claim 12 or 13.

15. The power system according to claim 14, characterized in that: The circuit breaker comprises a first digital input port and a first digital output port, and each of the inverters comprises a second digital input port and a second digital output port respectively; The first digital output port is electrically connected to each of the second digital input ports, and the first digital input port is electrically connected to each of the second digital output ports.

16. An inverter scheduling method, characterized in that: The inverter scheduling method is applied to the power system according to claim 15; The inverter scheduling method comprises: The circuit breaker sends a scheduling instruction to each of the second digital input ports respectively through the first digital output port; Each of the inverters completes a corresponding scheduling operation according to the received scheduling instruction, and sends a feedback instruction to the first digital input port through the second digital output port; The circuit breaker determines the completion status of the corresponding scheduling operation according to each of the received feedback instructions.

17. The inverter scheduling method according to claim 16, characterized in that: The dispatching instruction includes a dry contact opening instruction representing the control of the inverter opening, a dry contact closing instruction representing the control of the inverter closing, or a pulse signal instruction representing the output power size of the control inverter.

18. The inverter scheduling method according to claim 16, characterized in that: Each of the inverters completes a corresponding scheduling operation according to the received scheduling instruction, and sends a feedback instruction to the first digital input port through the second digital output port, including: For each of the inverters, If the inverter successfully completes the corresponding scheduling operation, the inverter sends a dry contact closing instruction indicating successful completion to the first digital input port through the corresponding second digital output port; If the inverter fails to successfully complete the corresponding scheduling operation, the inverter sends a dry contact port instruction indicating unsuccessful completion to the first digital input port through the corresponding second digital output port; The circuit breaker determines the completion status of the corresponding scheduling operation according to each of the received feedback instructions, including: For each of the feedback instructions, If the feedback instruction is a dry contact closing instruction, a completion status indicating successful completion is obtained; If the feedback instruction is a dry contact disconnection instruction, a completion status indicating unsuccessful completion is obtained.

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