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

Abstract

The present invention relates to the field of power control technology. The present invention provides an inverter control method, system, power system and inverter scheduling method. The method includes the following steps executed by a circuit breaker: obtaining a preset change curve sent by a master station; determining a target power according to the current time and the preset change curve; and performing output control on a plurality of inverters according to the target power. The master station can send a preset change curve of power-time mapping representing the power demand for 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 perform output control on a plurality of inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to achieve the output control of a plurality of inverters for a period of time, without the need to frequently transfer control between the master station and the inverters. The communication is simple and the situation of command loss is not likely to occur, ultimately improving the reliability of control.

Description

Technical Field

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

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

[0003] The effect of the traditional control method is poor, resulting in easy errors in the control of the inverters. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the present invention provides an inverter control method, a system, a power system and an inverter scheduling method.

[0005] In a first aspect, in an embodiment, the present invention provides an inverter control method, which 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 multiple inverters respectively; the inverter control method includes the following steps executed by the circuit breaker:

[0006] Obtain a preset change curve of the power-time mapping sent by the master station;

[0007] Determine the target power according to the current time and the preset change curve;

[0008] Perform output control on the multiple inverters according to the target power, so that the total power output by the multiple inverters can meet the target power.

[0009] In an embodiment, determining the target power according to the current time and the preset change curve includes:

[0010] Match the corresponding sample time in the preset change curve according to the current time;

[0011] Determine the sample power corresponding to the sample time in the preset change curve as the target power.

[0012] In an embodiment, performing output control on the multiple inverters according to the target power includes:

[0013] Obtain the current total power of the multiple inverters;

[0014] Determine 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;

[0015] Perform output control on the multiple inverters according to the power adjustment strategy.

[0016] In one embodiment, according to a power adjustment strategy, output control is performed on multiple inverters, including:

[0017] If the power adjustment direction indicates that the multiple inverters need to increase the total power, determine the inverters among the multiple inverters whose switch states are in the off state;

[0018] According to the power adjustment magnitude, determine at least one inverter whose switch state is in the off state as the first target inverter;

[0019] Control the switch state of the first target inverter to the on state, and perform output control on the first target inverter so that the total power output by the first target inverter can meet the power represented by the power adjustment magnitude.

[0020] In one embodiment, if the power adjustment direction indicates that the multiple inverters need to increase the total power, determining the inverters among the multiple inverters whose switch states are in the off state includes:

[0021] If the power adjustment direction indicates that the multiple inverters need to increase the total power, determine the inverters among the multiple inverters whose switch states are in the on state;

[0022] According to a first preset power, determine the remaining power of each inverter whose switch state is in the on state;

[0023] If the sum of the remaining powers of the inverters whose switch states are in the on state cannot meet the power represented by the power adjustment magnitude, determine the inverters among the multiple inverters whose switch states are in the off state.

[0024] In one embodiment, after the step of determining the remaining power of each inverter whose switch state is in the on state according to the first preset power, the inverter control method further includes:

[0025] If the sum of the remaining powers of the inverters whose switch states are in the on state can meet the power represented by the power adjustment magnitude, determine at least one inverter whose switch state is in the on state as the second target inverter according to the power adjustment magnitude;

[0026] Perform output control on the second target inverter so that the increased total power of the second target inverter can meet the power represented by the power adjustment magnitude.

[0027] In one embodiment, determining at least one inverter whose switch state is in the off state as the first target inverter according to the power adjustment magnitude includes:

[0028] Determine the first conversion time when each inverter whose switch state is in the off state is converted to the off state;

[0029] Determine the startup priority of each inverter with the switch state being off according to the first conversion time;

[0030] Determine at least one inverter with the switch state being off as the first target inverter according to the power adjustment magnitude and the startup priority of each inverter with the switch state being off;

[0031] Among them, the earlier the first conversion time of the inverter, the higher the corresponding startup priority.

[0032] In one embodiment, output control of multiple inverters is performed according to a power adjustment strategy, including:

[0033] If the power adjustment direction indicates that multiple inverters need to reduce the total power, determine at least one inverter with the switch state being on as the third target inverter according to the power adjustment magnitude;

[0034] Control the switch state of the third target inverter to be off so that the total power interrupted by the third target inverter can meet the power represented by the power adjustment magnitude.

[0035] In one embodiment, if the power adjustment direction indicates that multiple inverters need to reduce the total power, determining at least one inverter with the switch state being on as the third target inverter according to the power adjustment magnitude includes:

[0036] If the power adjustment direction indicates that multiple inverters need to reduce the total power, determine the excess power of each inverter with the switch state being on according to the second preset power;

[0037] If the sum of the excess powers of the inverters with the switch state being on cannot meet the power represented by the power adjustment magnitude, determine at least one inverter with the switch state being on as the third target inverter.

[0038] In one embodiment, after the step of determining the excess power of each inverter with the switch state being on according to the second preset power, the inverter control method further includes:

[0039] If the sum of the excess powers of the inverters with the switch state being on can meet the power represented by the power adjustment magnitude, determine at least one inverter with the switch state being on as the fourth target inverter;

[0040] Perform output control on the fourth target inverter so that the total power reduced by the fourth target inverter can meet the power represented by the power adjustment magnitude.

[0041] In one embodiment, determining at least one inverter with the switch state being on as the third target inverter according to the power adjustment magnitude includes:

[0042] Determine the second conversion time for an inverter with its switch state being the on state to convert to the on state;

[0043] Based on the second conversion time, determine the shutdown priority of each inverter with its switch state being the on state;

[0044] Based on the power adjustment magnitude and the shutdown priority of each inverter with its switch state being the on state, determine at least one inverter with its switch state being the on state as the third target inverter.

[0045] In a second aspect, in an embodiment, the present invention provides 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 circuit breaker is used to execute the inverter control method in any of the above embodiments.

[0046] In an 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 through a power line;

[0047] The intermediate device is used to communicate with the circuit breaker based on the power line and through a carrier communication method.

[0048] In a third aspect, in an embodiment, the present invention provides a power system, including a plurality of inverters and the inverter control system in any of the above embodiments.

[0049] In an embodiment, the circuit breaker includes a first digital input port and a first digital output port, and each inverter respectively includes a second digital input port and a second digital output port;

[0050] 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.

[0051] In a fourth aspect, in an embodiment, the present invention provides an inverter scheduling method. The inverter scheduling method is applied to the power system in the above embodiment; the inverter scheduling method includes:

[0052] The circuit breaker sends scheduling instructions to each second digital input port respectively through the first digital output port;

[0053] Each inverter completes corresponding scheduling operations according to the received scheduling instructions, and sends feedback instructions to the first digital input port through the second digital output port;

[0054] The circuit breaker determines the completion status of the corresponding scheduling operation according to each received feedback instruction.

[0055] In one embodiment, the scheduling instruction includes a dry contact disconnection instruction indicating the control of the inverter to turn on, a dry contact closure instruction indicating the control of the inverter to turn off, or a pulse signal instruction indicating the output power magnitude of the control inverter.

[0056] In one embodiment, each inverter completes the corresponding scheduling operation according to the accessed scheduling instruction, and sends a feedback instruction to the first digital input port through the second digital output port, including:

[0057] For each inverter,

[0058] If the inverter successfully completes the corresponding scheduling operation, it sends a dry contact closure instruction indicating successful completion to the first digital input port through the corresponding second digital output port;

[0059] If the inverter fails to successfully complete the corresponding scheduling operation, it sends a dry contact port instruction indicating unsuccessful completion to the first digital input port through the corresponding second digital output port;

[0060] The circuit breaker determines the completion status of the corresponding scheduling operation according to each accessed feedback instruction, including:

[0061] For each feedback instruction,

[0062] If the feedback instruction is a dry contact closure instruction, a completion status indicating successful completion is obtained;

[0063] If the feedback instruction is a dry contact disconnection instruction, a completion status indicating unsuccessful completion is obtained.

[0064] Through the above inverter control method, system, power system and inverter scheduling method, the master station can send a preset change curve of power-time mapping representing the power demand for 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 perform output control on multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to achieve output control of multiple inverters for a period of time, without the need to frequently transfer control between the master station and the inverter. The communication is simple and the situation of command loss is not likely to occur, ultimately improving the reliability of control. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0066] Figure 1Schematic diagram of the structure of the power system in an embodiment of the present invention;

[0067] Figure 2 Schematic diagram of the preset change curve in an embodiment of the present invention;

[0068] Figure 3 Schematic diagram of the connection mode of the circuit breaker with the master station and the inverter respectively in an embodiment of the present invention;

[0069] Figure 4 Schematic flow chart of the inverter scheduling method in an embodiment of the present invention. Detailed implementation manners

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0071] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and 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 a limitation of 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 the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "a plurality" means two or more, unless otherwise specifically defined. In this application, the term "exemplary" is used to mean "serving as an example, illustration, or description". Any embodiment described as "exemplary" in this application is not necessarily to be construed as more preferred or more advantageous than other embodiments. In order for any person skilled in the art to implement and use the present invention, the following description is given. In the following description, details are set forth for the purpose of explanation. It should be understood that those skilled in the art can recognize that the present invention can be implemented without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid unnecessary details from obscuring the description of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed in this application.

[0072] In a first aspect, as Figure 1 shown, in one embodiment, the present invention provides an inverter control method, which is applied to an inverter control system.

[0073] As Figure 1 shown, the inverter control system includes a master station, a circuit breaker electrically connected to the master station and respectively used for electrically connecting to a plurality of inverters.

[0074] Among them, the master station is responsible for the overall control of the power grid. The circuit breaker is arranged between the master station and the inverter to achieve the purpose of control transfer. The inverter can invert the power generated by the photovoltaic into alternating current for output to the power grid. In Figure 1 , setting three inverters is only an example. In other embodiments, more or fewer inverters may be included.

[0075] The inverter control method includes the following steps executed by the circuit breaker:

[0076] Obtain a preset change curve of the power-time mapping sent by the master station.

[0077] Among them, the master station can obtain the preset change curve according to historical data.

[0078] Among them, the historical data may include historical power, historical power consumption, and specific moments corresponding to a certain time period. For example, if the preset change curve is a change curve of the power-time mapping within 24 hours, the master station can respectively determine the power at multiple moments within 24 hours, and then obtain the preset change curve by means of curve fitting.

[0079] As an example, the preset change curve fitted by the master station is as Figure 2 shown. In the corresponding vertical coordinate system of the preset change curve, the horizontal axis of the vertical coordinate system is time t (unit: h), and the vertical axis of the vertical coordinate system is power P (unit: w).

[0080] Determine the target power according to the current time and the preset change curve.

[0081] As mentioned in the above steps, 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 in the preset change curve according to the current time.

[0082] Perform output control on a plurality of inverters according to the target power, so that the total power output by the plurality of inverters can meet the target power.

[0083] Among them, it should be noted that before controlling the outputs of multiple inverters, there are corresponding power outputs for the multiple inverters themselves. The total power output by the multiple inverters can be understood as the current total power, which is controlled by the historical target power obtained by the previous circuit breaker. The circuit breaker needs to perform specific power control according to the magnitude relationship between the currently determined target power and the current total power being executed by the multiple inverters. For example, if the target power is greater than the current total power, it is necessary to control the multiple inverters to increase the total power; if the target power is equal to the current total power, it is necessary to control the multiple inverters to maintain the total power; if the target power is less than the current total power, it is necessary to control the multiple inverters to decrease the total power.

[0084] Among them, whether it is to control the multiple inverters to increase the total power, maintain the total power, or decrease the total power, it is necessary to ensure that the total power finally output by the multiple inverters can meet the target power.

[0085] Through the above inverter control method, the master station can send a preset change curve of power-time mapping representing the power demand for 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 perform output control on the multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to achieve the output control of the multiple inverters for a period of time, without the need to frequently transfer control between the master station and the inverters. The communication is simple and the situation of command loss is not likely to occur, ultimately improving the reliability of the control.

[0086] In one embodiment, determining the target power according to the current time and the preset change curve includes:

[0087] Matching the corresponding sample time in the preset change curve according to the current time;

[0088] Determining the sample power corresponding to the sample time in the preset change curve as the target power.

[0089] Among them, as mentioned in the above embodiment, 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. At this time, relevant processing needs to be performed on the current time.

[0090] Specifically, if the current time is 15:00 on January 1st, and the preset change curve sent by the main station is used to represent the power demand from 09:00 on January 1st to 08:00 on January 2nd, then in the preset change curve, when the horizontal axis is 1h, the corresponding real-time value is 09:00 on January 1st, and when the horizontal axis is 2h, the corresponding real-time value is 10:00 on January 1st. Therefore, if the current time is 15:00 on January 1st, 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.

[0091] Of course, in other embodiments, when the representation of the current time is different, the corresponding target power can also be determined based on other methods according to the preset change curve and the current time.

[0092] In one embodiment, output control of multiple inverters is performed according to the target power, including:

[0093] Obtain the current total power of multiple inverters;

[0094] Determine the power adjustment strategy of multiple inverters according to the target power and the current total power;

[0095] Perform output control on multiple inverters according to the power adjustment strategy.

[0096] As mentioned in the above embodiment, when performing control according to the target power, the current total power of multiple inverters can be further considered, 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 specifically adjust the power of multiple inverters, the output of multiple inverters can be directly controlled according to the power adjustment strategy to adjust the output power.

[0097] Specifically, the power adjustment strategy includes the power adjustment direction and the power adjustment magnitude. The power adjustment direction is used to indicate whether multiple inverters need to increase the total power, maintain the total power, or decrease the total power, and the power adjustment magnitude 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 magnitude is specifically used to indicate the amount of power to be increased. For example, when the power adjustment direction is used to indicate that multiple inverters need to decrease the total power, the power adjustment magnitude is specifically used to indicate the amount of power to be decreased.

[0098] In one embodiment, output control of multiple inverters is performed according to the power adjustment strategy, including:

[0099] If the power adjustment direction indicates that multiple inverters need to increase the total power, determine the inverters among the multiple inverters whose switch states are in the off state.

[0100] Among them, when multiple inverters need to increase the total power, if there are inverters among the multiple inverters whose switch states are in the off state, these inverters can be considered to be turned on to bear the increased total power.

[0101] Determine at least one inverter whose switch state is in the off state as the first target inverter according to the magnitude of the power adjustment.

[0102] Among them, when the power adjustment direction is used to indicate that multiple inverters need to increase the total power, at this time, the magnitude of the power adjustment is specifically used to indicate the amount of power that needs to be increased. Therefore, according to the magnitude of the power adjustment, it can be determined how many inverters whose switch states are in the off state need to be turned on to meet the demand, and the inverters that need to be turned on are determined as the first target inverters.

[0103] Control the switch state of the first target inverter to the on state, and perform output control on the first target inverter so that the total power output by the first target inverter can meet the power characterized by the magnitude of the power adjustment.

[0104] Among them, the output power of each first target inverter is adjustable. Therefore, after converting the switch state of the first target inverter to the on state, it is also necessary to further perform output control on the first target inverter to allocate the power output by each first target inverter according to the magnitude of the power adjustment, and finally ensure that the total power output by the first target inverter can meet the power characterized by the magnitude of the power adjustment.

[0105] In one embodiment, if the power adjustment direction indicates that multiple inverters need to increase the total power, determining the inverters among the multiple inverters whose switch states are in the off state includes:

[0106] If the power adjustment direction indicates that multiple inverters need to increase the total power, determine the inverters among the multiple inverters whose switch states are in the on state.

[0107] As mentioned in the above embodiment, when the total power needs to be increased, inverters whose switch states are in the off state can be directly considered to be turned on. However, in this embodiment, the working efficiency of the inverters can be further considered, and inverters whose switch states are in the on state but have a low working efficiency due to low output power can be considered to bear the increased total power.

[0108] Determine the remaining power of each inverter whose switch state is in the on state according to the first preset power.

[0109] Among them, the first preset power can be used to characterize the operating efficiency of the inverter. When the output power of the inverter is lower than the first preset power, it can be considered that the operating efficiency of the inverter is relatively low. Therefore, the remaining power corresponding to when the output power of each inverter with an on switch state can be increased to the first preset power can be further determined according to the first preset power.

[0110] If the sum of the remaining powers of the inverters with an on switch state cannot meet the power characterized by the power adjustment magnitude, then determine the inverters with an off switch state among the multiple inverters.

[0111] Among them, if it is determined that the sum of the remaining powers cannot meet the power characterized by the power adjustment magnitude, it means that the currently on inverters cannot fully bear the increased total power only by increasing the output power to the first preset power. For this situation, the inverters with an off switch state can be further considered to be turned on.

[0112] It should be noted that in this embodiment, if it is determined that the sum of the remaining powers cannot meet the power characterized by the power adjustment magnitude, in addition to considering turning on the inverters with an off switch state to fully bear the increased total power; the inverters with an on switch state can also bear a part of the increased total power based on the improvement of the operating efficiency, and turn on fewer inverters with an off switch state to bear the remaining part of the increased total power.

[0113] In one embodiment, after the step of determining the remaining power of each inverter with an on switch state according to the first preset power, the inverter control method further includes:

[0114] If the sum of the remaining powers of the inverters with an on switch state can meet the power characterized by the power adjustment magnitude, then at least one inverter with an on switch state is determined as the second target inverter according to the power adjustment magnitude.

[0115] Among them, if it is determined that the sum of the remaining powers can meet the power characterized by the power adjustment magnitude, it means that the currently on inverters can fully bear the increased total power only by increasing the output power to the first preset power. For this situation, at least one inverter with an on switch state can be directly determined as the second target inverter according to the power adjustment magnitude and the remaining power of each inverter.

[0116] Perform output control on the second target inverter so that the increased total power of the second target inverter can meet the power characterized by the power adjustment magnitude.

[0117] 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, mainly the power output by the second target inverter is increased, and finally it is ensured that the total increased power of the second target inverter can meet the power characterized by the power adjustment magnitude.

[0118] In one embodiment, determining at least one inverter with a closed switch state as the first target inverter according to the power adjustment magnitude includes:

[0119] Determine the first conversion time when each inverter with a closed switch state is converted to the closed state.

[0120] Among them, each inverter with a closed switch state is converted from the on state, and the time of conversion is the first conversion time.

[0121] Determine the start priority of each inverter with a closed switch state according to the first conversion time.

[0122] Among them, overusing a certain inverter will cause the lifespan of the inverter to decrease, and then reduce the lifespan of the entire power system. Therefore, in order to make the use of each inverter more balanced, the inverter that enters the closed state first can be preferentially turned on. To achieve this goal, after determining the first conversion time of each inverter, the corresponding start priority can be determined according to the first conversion time, and the inverter with a higher start priority is preferentially turned on.

[0123] Among them, combined with the purpose of balance, it can be determined that the inverter with an earlier first conversion time has a higher start priority.

[0124] Determine at least one inverter with a closed switch state as the first target inverter according to the power adjustment magnitude and the start priority of each inverter with a closed switch state.

[0125] Among them, if one inverter needs to be turned on, turn on the inverter with the highest start priority. Similarly, if two inverters need to be turned on, turn on the two inverters with the highest start priority.

[0126] In one embodiment, performing output control on multiple inverters according to the power adjustment strategy includes:

[0127] If the power adjustment direction indicates that multiple inverters need to reduce the total power, determine at least one inverter with an on switch state as the third target inverter according to the power adjustment magnitude.

[0128] Among them, when multiple inverters need to reduce the total power, some inverters can be directly turned off. When the power adjustment direction is used to indicate that multiple inverters need to reduce the total power, the power adjustment magnitude is specifically used to indicate the amount of power that needs to be reduced. Thus, it is possible to determine how many inverters with the switch state of on need to be turned off to meet the requirement according to the power adjustment magnitude, and the inverters that need to be turned off are determined as the third target inverters.

[0129] Control the switch state of the third target inverters to the off state so that the total power interrupted by the third target inverters can meet the power characterized by the power adjustment magnitude.

[0130] Among them, compared with turning on the inverters, turning off the inverters can directly interrupt the power output by the inverters, so there is no need to further control the output of the inverters. Finally, it is only necessary to ensure that the total power interrupted by the third target inverters can meet the power characterized by the power adjustment magnitude.

[0131] In one embodiment, if the power adjustment direction indicates that multiple inverters need to reduce the total power, then according to the power adjustment magnitude, at least one inverter with the switch state of on is determined as the third target inverter, including:

[0132] If the power adjustment direction indicates that multiple inverters need to reduce the total power, then according to the second preset power, the excess power of each inverter with the switch state of on is determined.

[0133] Among them, as mentioned in the above embodiment, when the total power needs to be reduced, inverters with the switch state of on can be directly turned off. However, in this embodiment, the load conditions of the inverters can be further considered. Inverters with the switch state of on but with certain potential hazards due to high output power can be considered to bear the reduced total power.

[0134] Among them, the second preset power can be used to characterize the load conditions of the inverters. When the output power of an inverter is higher than the second preset power, it can be considered that there are certain potential safety hazards in the load conditions of the inverter. Therefore, the excess power corresponding to when the output power of each inverter with the switch state of on can be reduced to the second preset power can be further determined according to the second preset power.

[0135] If the sum of the excess powers of the inverters with the switch state of on cannot meet the power characterized by the power adjustment magnitude, then at least one inverter with the switch state of on is determined as the third target inverter.

[0136] Among them, if the sum of the determined excess powers cannot satisfy the power represented by the power adjustment magnitude, it indicates that the currently turned-on inverters cannot fully bear the reduced total power only by reducing the output power to the second preset power. For this situation, the inverters with the switch state being on can be further considered to be turned off.

[0137] It should be noted that in this embodiment, if the sum of the determined excess powers cannot satisfy the power represented by the power adjustment magnitude, in addition to considering turning off the inverters with the switch state being on to fully bear the increased total power; the inverters with the switch state being on can also bear a part of the reduced total power based on the load condition to reduce the safety hazard, and turn off fewer inverters with the switch state being on to bear the remaining part of the reduced total power.

[0138] In one embodiment, after the step of determining the excess power of each inverter with the switch state being on according to the second preset power, the inverter control method further includes:

[0139] If the sum of the excess powers of the inverters with the switch state being on can satisfy the power represented by the power adjustment magnitude, at least one inverter with the switch state being on is determined as the fourth target inverter.

[0140] Among them, if the sum of the determined excess powers can satisfy the power represented by the power adjustment magnitude, it indicates that the currently turned-on inverters can fully bear the reduced total power only by reducing the output power to the second preset power. For this situation, at least one inverter with the switch state being on can be directly determined as the fourth target inverter according to the power adjustment magnitude and the excess power of each inverter.

[0141] Perform output control on the fourth target inverter so that the total power reduced by the fourth target inverter can satisfy the power represented by the power adjustment magnitude.

[0142] Among them, since the fourth target inverter has been in the on state and has a certain power output before this control, in this control, mainly the power output by the fourth target inverter is reduced, and finally it is ensured that the total power reduced by the fourth target inverter can satisfy the power represented by the power adjustment magnitude.

[0143] In one embodiment, determining at least one inverter with the switch state being on as the third target inverter according to the power adjustment magnitude includes:

[0144] Determine the second conversion time when each inverter with the switch state being on is converted to the on state.

[0145] Among them, each inverter with an on switch state is converted from an off state, and the time of conversion is the second conversion time.

[0146] Determine the shutdown priority of each inverter with an on switch state according to the second conversion time.

[0147] Among them, overusing a certain inverter will cause the lifespan of the inverter to decrease, and then reduce the lifespan of the entire power system. Therefore, in order to make the use of each inverter more balanced, the inverter that enters the on state first can be preferentially shut down. 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 is preferentially shut down.

[0148] Among them, combined with the purpose of balance, it can be determined that the inverter with an earlier second conversion time has a higher shutdown priority.

[0149] Determine at least one inverter with an on switch state as the third target inverter according to the power adjustment magnitude and the shutdown priority of each inverter with an on switch state.

[0150] Among them, if one inverter needs to be shut down, the inverter with the highest shutdown priority is shut down. Similarly, if two inverters need to be shut down, the two inverters with the highest shutdown priorities are shut down.

[0151] Combined with the above embodiments, the breaker controls multiple inverters in a "first-on, first-off, sequential cycle" control mode. For example, there are 10 inverters numbered 1 - 10 under a breaker somewhere. Suppose the power provided by the preset change curve at 8 am is 2000 Kw. At this time, inverters 1 - 4 are sequentially turned on and each outputs 40%, which can meet the needs; at 12 noon, the power provided by the preset change curve is 5000 Kw. At this time, inverters 5 - 8 are sequentially turned on and each outputs 60%, which can meet the needs; by 5 pm, the power provided by the preset change curve is 200 Kw. Since the first inverters to be turned on are 1 - 4, according to the control principle, inverters 1 - 4 are preferentially shut down. If subsequent inverters need to be turned on, they continue to be turned on in the order of 9, 10, 1, 2. If subsequent inverters need to be shut down, the previously turned-on inverters 5 - 8 are preferentially shut down.

[0152] Second aspect, as Figure 1 shown, in one embodiment, the present invention provides an inverter control system. The inverter control system includes a master station, a breaker electrically connected to the master station and used to be electrically connected to multiple inverters respectively; the breaker is used to execute the inverter control method in any of the above embodiments.

[0153] Through the above inverter control system, the master station can send a preset change curve of the power-time mapping representing the power demand for 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 perform output control on multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to achieve the output control of multiple inverters for a period of time, without the need to frequently transfer control between the master station and the inverters. The communication is simple and the command loss is not likely to occur, ultimately improving the reliability of the control.

[0154] As Figure 3 shown, 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 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 carrier communication.

[0155] Among them, the intermediate device includes a front-end machine, a concentrator / fusion terminal, etc.

[0156] In a third aspect, as Figure 1 shown, in one embodiment, the present invention provides a power system, including a plurality of inverters and the inverter control system in any of the above embodiments.

[0157] Through the above power system, the master station can send a preset change curve of the power-time mapping representing the power demand for 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 perform output control on multiple inverters according to the target power. The circuit breaker in this application only needs to communicate with the master station once to achieve the output control of multiple inverters for a period of time, without the need to frequently transfer control between the master station and the inverters. The communication is simple and the command loss is not likely to occur, ultimately improving the reliability of the control.

[0158] As Figure 3 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 respectively.

[0159] Among them, the first digital output port DO_1 is electrically connected to each second digital input port DI_2 respectively, and the first digital input port DI_1 is electrically connected to each second digital output port DO_2 respectively.

[0160] Among them, in addition to using the DI / DO communication method between the circuit breaker and the inverter, other communication methods can also be used, such as using 485 communication.

[0161] 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:

[0162] The circuit breaker sends scheduling instructions to each second digital input port through the first digital output port;

[0163] Each inverter completes corresponding scheduling operations according to the received scheduling instructions, and sends feedback instructions to the first digital input port through the second digital output port;

[0164] The circuit breaker determines the completion status of the corresponding scheduling operation according to each received feedback instruction.

[0165] Among them, referring to Figure 3 , when the circuit breaker controls the inverter to turn on and off, it outputs instructions from its first digital output port DO_1 to the second digital input port DI_2 of the inverter, and the feedback of the inverter outputs instructions from the second digital output port DO_2 to the first digital input port DI_1 of the circuit breaker. The circuit breaker and the master station perform data interaction through the HPLC power line carrier communication method.

[0166] In one embodiment, the scheduling instructions include a dry contact disconnection instruction indicating controlling the inverter to turn on, a dry contact closing instruction indicating controlling the inverter to turn off, or a pulse signal instruction indicating controlling the output power magnitude of the inverter.

[0167] In one embodiment, each inverter completes corresponding scheduling operations according to the received scheduling instructions, and sends feedback instructions to the first digital input port through the second digital output port, including:

[0168] For each inverter,

[0169] 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;

[0170] If the inverter fails to successfully complete the corresponding scheduling operation, it sends a dry contact port instruction indicating unsuccessful completion to the first digital input port through the corresponding second digital output port;

[0171] The circuit breaker determines the completion status of the corresponding scheduling operation according to each received feedback instruction, including:

[0172] For each feedback instruction,

[0173] If the feedback instruction is a dry contact closing instruction, a completion status indicating successful completion is obtained;

[0174] If the feedback instruction is a dry contact disconnection instruction, a completion status indicating unsuccessful completion is obtained.

[0175] In summary of the above embodiments, as Figure 4 shown, under the default state, multiple inverters are connected to the grid for output. When the master station needs to control the inverters, scheduling instructions are sent to the circuit breaker through power line carrier. When it is necessary to control the opening / closing operation of the inverter, the first digital output port DO_1 of the circuit breaker outputs the scheduling instruction to the inverter. The closing instruction is a closed dry contact, and the opening instruction is an open dry contact. When it is necessary to adjust the output power of the inverter, the first digital output port DO_1 of the circuit breaker outputs a pulse signal of 1 hZ to 100 hZ to the inverter, and the pulse frequency corresponds to the percentage of the rated power of the PV grid connection. After a scheduling instruction is completed, the inverter feeds back a feedback signal to the circuit breaker through the second digital output port DO_2. If the scheduling is successful, the inverter outputs a closed dry contact signal with a duration > 3S; if the scheduling fails, the inverter outputs an open dry contact signal.

[0176] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For parts not described in detail in a certain embodiment, reference may be made to the detailed descriptions of other embodiments above, and details will not be repeated here.

[0177] The above has introduced in detail an inverter control method, system, power system, and inverter scheduling method provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, based on the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

[0178] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope described in this specification.

Claims

1. An inverter control method, characterized in that, The inverter control method is applied to 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 inverter control method includes the following steps executed by the circuit breaker: Obtain a preset change curve of power mapped to time sent by the master station; Determine the target power according to the current time and the preset change curve; Perform output control on the multiple inverters according to the target power, so that the total power output by the multiple inverters can meet the target power; The performing output control on the multiple inverters according to the target power includes: Obtain the current total power of the multiple inverters; Determine 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; Perform output control on the multiple inverters according to the power adjustment strategy; The performing output control on the multiple inverters according to the power adjustment strategy includes: If the power adjustment direction indicates that the multiple inverters need to increase the total power, determine the inverters with the switch state being off among the multiple inverters; Determine at least one inverter with the switch state being off as the first target inverter according to the power adjustment magnitude; Control the switch state of the first target inverter to be on, and perform output control on the first target inverter, so that the total power output by the first target inverter can meet the power indicated by the power adjustment magnitude; The determining the inverters with the switch state being off among the multiple inverters if the power adjustment direction indicates that the multiple inverters need to increase the total power includes: If the power adjustment direction indicates that the multiple inverters need to increase the total power, determine the inverters with the switch state being on among the multiple inverters; Determine the remaining power of each inverter with the switch state being on according to a first preset power; If the sum of the remaining powers of the inverters with the switch state being on cannot meet the power indicated by the power adjustment magnitude, determine the inverters with the switch state being off among the multiple inverters; The performing output control on the multiple inverters according to the power adjustment strategy includes: If the power adjustment direction indicates that the multiple inverters need to decrease the total power, determine at least one inverter with the switch state being on as the third target inverter according to the power adjustment magnitude; Control the switch state of the third target inverter to be off, so that the total power interrupted by the third target inverter can meet the power indicated by the power adjustment magnitude; The determining at least one inverter with the switch state being on as the third target inverter according to the power adjustment magnitude if the power adjustment direction indicates that the multiple inverters need to decrease the total power includes: If the power adjustment direction indicates that the multiple inverters need to decrease the total power, determine the excess power of each inverter with the switch state being on according to a second preset power; If the sum of the excess powers of the inverters with the switch state being the on state cannot satisfy the power represented by the power adjustment magnitude, at least one inverter with the switch state being the on state is determined as the third target inverter.

2. The inverter control method according to claim 1, wherein, The determining the target power according to the current time and the preset change curve includes: Matching the corresponding sample time in the preset change curve according to the current time; Determining the sample power corresponding to the sample time in the preset change curve as the target power.

3. The inverter control method according to claim 1, characterized in that, After the step of determining the remaining power of each inverter with the switch state being the on state according to the preset power, the inverter control method further includes: If the sum of the remaining powers of the inverters with the switch state being the on state can satisfy the power represented by the power adjustment magnitude, at least one inverter with the switch state being the on state is determined as the second target inverter according to the power adjustment magnitude; Performing output control on the second target inverter so that the total power increased by the second target inverter can satisfy the power represented by the power adjustment magnitude.

4. The inverter control method according to claim 1, characterized in that, The determining at least one inverter with the switch state being the off state as the first target inverter according to the power adjustment magnitude includes: Determining the first conversion time when each inverter with the switch state being the off state is converted to the off state; Determining the turn-on priority of each inverter with the switch state being the off state according to the first conversion time; Determining at least one inverter with the switch state being the off state as the first target inverter according to the power adjustment magnitude and the turn-on priority of each inverter with the switch state being the off state; Wherein, the earlier the first conversion time of the inverter, the higher the corresponding turn-on priority.

5. The inverter control method according to claim 1, wherein, After the step of determining the excess power of each inverter with the switch state being the on state according to the second preset power, the inverter control method further includes: If the sum of the excess powers of the inverters with the switch state being the on state can satisfy the power represented by the power adjustment magnitude, at least one inverter with the switch state being the on state is determined as the fourth target inverter; Performing output control on the fourth target inverter so that the total power decreased by the fourth target inverter can satisfy the power represented by the power adjustment magnitude.

6. The inverter control method according to claim 1, characterized in that, The determining at least one inverter with the switch state being the on state as the third target inverter according to the power adjustment magnitude includes: Determining the second conversion time when each inverter with the switch state being the on state is converted to the on state; Determining the turn-off priority of each inverter with the switch state being the on state according to the second conversion time; Determining at least one inverter with the switch state being the on state as the third target inverter according to the power adjustment magnitude and the turn-off priority of each inverter with the switch state being the on state.

7. 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 for electrically connecting to a plurality of inverters respectively; the circuit breaker is used to execute the inverter control method according to any one of claims 1 to 6.

8. The inverter control system according to claim 7, characterized in that, The inverter system further includes an intermediate device, which is electrically connected to the master station, and the intermediate device is electrically connected to the circuit breaker through a power line; The intermediate device is configured to communicate with the circuit breaker based on the power line and by means of carrier communication.

9. A power system, characterized in that, Comprising a plurality of inverters and the inverter control system according to claim 7 or 8.

10. The power system according to claim 9, characterized in that, The circuit breaker includes a first digital input port and a first digital output port, and each inverter includes 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 respectively, and the first digital input port is electrically connected to each of the second digital output ports respectively.

11. An inverter scheduling method, characterized in that, The inverter scheduling method is applied to the power system according to claim 9; The inverter scheduling method includes: The circuit breaker sends scheduling instructions to each second digital input port through the first digital output port respectively; Each inverter completes corresponding scheduling operations according to the received scheduling instructions, and sends feedback instructions 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.

12. The inverter scheduling method according to claim 11, wherein The scheduling instructions include a dry contact disconnection instruction indicating to control the inverter to turn on, a dry contact closure instruction indicating to control the inverter to turn off, or a pulse signal instruction indicating to control the output power magnitude of the inverter.

13. The inverter scheduling method according to claim 11, wherein Each of the inverters completes corresponding scheduling operations according to the received scheduling instructions, and sends feedback instructions 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 closure 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, it 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 closure 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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