CN112688275A - Inverter protection method and device and terminal equipment - Google Patents
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Abstract
The invention is suitable for the technical field of inverter protection, and provides an inverter protection method, an inverter protection device and terminal equipment, wherein the method comprises the following steps: acquiring an output voltage sampling value and an output current sampling value of an inverter; calculating an output voltage effective value of the inverter according to the output voltage sampling value; calculating the active power of the inverter according to the output voltage sampling value and the output current sampling value; when the output voltage effective value and the active power meet a first preset condition, and the duration time of the first preset condition is longer than the output undervoltage protection time, triggering undervoltage protection action; the first preset condition is that the effective value of the output voltage is smaller than the undervoltage protection threshold value and the active power is larger than the power threshold value. According to the invention, the first preset condition and the condition that the duration time meeting the first preset condition is longer than the output undervoltage protection time are used as the condition that the inverter triggers the undervoltage protection action, so that whether the inverter needs to trigger the undervoltage protection action or not can be accurately judged, and the reliability of the inverter protection method is improved.
Description
Technical Field
The invention belongs to the technical field of inverter protection, and particularly relates to an inverter protection method, an inverter protection device and terminal equipment.
Background
The existing inverter protection mainly comprises: overcurrent protection, overvoltage protection, undervoltage protection, short-circuit protection on the output alternating current side and the like. The existing undervoltage protection logic generally determines whether to trigger undervoltage protection action by judging whether the voltage is lower than a threshold value within a certain time; the conventional short-circuit protection logic on the output ac side generally determines whether to trigger a short-circuit protection action by judging whether the voltage is lower than a threshold value and the current is higher than the threshold value within a certain time.
In the process of implementing the invention, the inventor finds that the prior art has at least the following problems: because both the under-voltage protection and the short-circuit protection need to judge whether the voltage is lower than a threshold value within a certain time to further determine whether to trigger a protection action, when the short-circuit protection logic is judged, if the short-circuit protection time is kept short, the short-circuit protection is triggered, and when the short-circuit protection action is switched to a bypass after being triggered, a Silicon Controlled Rectifier (SCR) device in the bypass is damaged due to short-circuit current; if the short-circuit protection time is maintained longer, the threshold value of the short-circuit protection logic and the threshold value of the undervoltage protection logic may overlap, so that undervoltage protection action is triggered when the short-circuit protection should be triggered, a false alarm is generated, and reliable protection of the inverter is not facilitated.
Disclosure of Invention
In view of this, embodiments of the present invention provide an inverter protection method, an inverter protection device, and a terminal device, so as to solve the problem of low reliability of the inverter protection method in the prior art.
A first aspect of an embodiment of the present invention provides an inverter protection method, including:
acquiring an output voltage sampling value and an output current sampling value of an inverter;
calculating an output voltage effective value of the inverter according to the output voltage sampling value; calculating the active power of the inverter according to the output voltage sampling value and the output current sampling value;
when the output voltage effective value and the active power meet a first preset condition, and the duration time of the first preset condition is longer than the output undervoltage protection time, triggering undervoltage protection action; the first preset condition is that the output voltage effective value is smaller than an undervoltage protection threshold value and the active power is larger than a power threshold value.
Optionally, the inverter protection method is applied to a scenario in which an air switch is disposed between the inverter and the load, and further includes:
when the output voltage sampling value and the output current sampling value meet a second preset condition, and the duration time of the second preset condition is longer than the short-circuit protection time, triggering a short-circuit protection action to disconnect the air switch; the second preset condition is that the output voltage sampling value is smaller than a short-circuit protection threshold value and the output current sampling value is larger than a current threshold value;
wherein the short-circuit protection time is greater than the output undervoltage protection time.
Optionally, a trip current of the air switch is less than or equal to the current threshold, and the air switch is turned off to protect the load when the output current sampling value is greater than the trip current;
the short-circuit protection time is longer than the time from closing to opening of the air switch.
Optionally, the calculating an effective value of the output voltage of the inverter according to the sampled value of the output voltage includes:
calculating the sum of squares of each output voltage sampling value according to a plurality of output voltage sampling values in an alternating current period to obtain the sum of squares of the plurality of output voltage sampling values;
and calculating the square root of the average value of the square sum of the plurality of output voltage sampling values to obtain the effective value of the output voltage of the inverter.
Optionally, the calculating an effective value of the output voltage of the inverter according to the sampled value of the output voltage includes:
acquiring a sampling interval of the output voltage sampling value;
according to the sampling interval, determining the output voltage peak value of the inverter according to the maximum value of a plurality of output voltage sampling values in an alternating current period;
and calculating the effective value of the output voltage of the inverter according to the peak value of the output voltage.
Optionally, the calculating an effective value of the output voltage of the inverter according to the peak value of the output voltage includes:
according to
Calculating an effective value of the output voltage of the inverter;
wherein, VrmsIs the effective value of the output voltage, VpIs the output voltage peak.
Optionally, the calculating the active power of the inverter according to the output voltage sampled value and the output current sampled value includes:
calculating an effective value of the output voltage of the inverter according to a plurality of output voltage sampling values in an alternating current period;
calculating an effective value of the output current of the inverter according to a plurality of output current sampling values in an alternating current period;
and calculating the active power of the inverter according to the effective value of the output voltage and the effective value of the output current.
A second aspect of an embodiment of the present invention provides an inverter protection device including:
the sampling module is used for acquiring an output voltage sampling value and an output current sampling value of the inverter;
the calculating module is used for calculating the output voltage effective value of the inverter according to the output voltage sampling value; calculating the active power of the inverter according to the output voltage sampling value and the output current sampling value;
the protection module is used for triggering an undervoltage protection action when the output voltage effective value and the active power meet a first preset condition and the duration time of the first preset condition is longer than the output undervoltage protection time; the first preset condition is that the output voltage effective value is smaller than an undervoltage protection threshold value and the active power is larger than a power threshold value.
A third aspect of the embodiments of the present invention provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the inverter protection method according to any one of the above items when executing the computer program.
A fourth aspect of embodiments of the present invention provides a computer-readable storage medium, which stores a computer program that, when executed by a processor, implements the steps of the inverter protection method as described in any one of the above.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: according to the method, the output voltage sampling value of the inverter is obtained, the output voltage effective value can be obtained through calculation according to the output voltage sampling value, the active power can be obtained through calculation according to the output current sampling value and the output voltage sampling value through obtaining the output current sampling value of the inverter, whether the output voltage effective value and the active power meet a first preset condition or not and whether the duration time meeting the first preset condition is longer than the output undervoltage protection time or not are judged, whether undervoltage protection action is triggered or not can be accurately judged, and the reliability of the inverter protection method is improved.
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In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic flow chart of an implementation of an inverter protection method provided by an embodiment of the present invention;
fig. 2 is a schematic diagram of an inverter protection device provided by an embodiment of the invention;
fig. 3 is a schematic diagram of a terminal device according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
Fig. 1 is a schematic flow chart of an implementation of the inverter protection method according to the embodiment of the present invention, which is detailed as follows.
Step S101, obtaining an output voltage sampling value and an output current sampling value of the inverter.
When the inverter is usually protected, the output voltage and the output current of the inverter are continuously sampled according to a set sampling frequency, and an output voltage sampling value and an output current sampling value are obtained.
In the prior art, it is usually detected whether an output voltage sampling value of an inverter and an output voltage effective value obtained according to a plurality of output voltage sampling values in an ac cycle are lower than an undervoltage protection threshold value within an output undervoltage protection time, so as to determine whether the inverter is in an impact undervoltage working condition. However, the inverter is usually provided with short-circuit protection, and the judgment logic of the short-circuit protection is to detect whether the output voltage sampling value of the inverter is lower than the short-circuit protection threshold value and whether the output current sampling value is higher than the current threshold value in the short-circuit protection time. When the output under-voltage protection time is equal to the short-circuit protection time, whether the inverter is in an impact under-voltage working condition or a short-circuit working condition can be accurately judged according to an output voltage sampling value and an output current sampling value of the inverter, and then the inverter is reliably protected. However, when the output under-voltage protection time is shorter than the short-circuit protection time, because the under-voltage protection threshold is generally larger than the short-circuit protection threshold, when the inverter is actually in the short-circuit working condition, if the inverter is judged to be in the impact under-voltage working condition only according to whether the output voltage sampling value or the output voltage effective value is lower than the under-voltage protection threshold in the output under-voltage time, the actual short-circuit working condition is mistakenly judged to be the impact under-voltage working condition, a false alarm is generated, and the inverter cannot be accurately and reliably protected.
Step S102, calculating an output voltage effective value of the inverter according to the output voltage sampling value; and calculating the active power of the inverter according to the output voltage sampling value and the output current sampling value.
As an embodiment of the present invention, calculating an effective value of an output voltage of an inverter according to a sampled value of the output voltage may include: calculating the sum of squares of each output voltage sampling value according to a plurality of output voltage sampling values in an alternating current period to obtain the sum of squares of the plurality of output voltage sampling values; and calculating the square root of the average value of the square sum of the plurality of output voltage sampling values to obtain the effective value of the output voltage of the inverter.
The effective voltage value is also called root mean square value and is a measure of the thermal effect of the sinusoidal voltage. When a resistor is connected to an alternating voltage source (sinusoidal waveform), the resistor dissipates a portion of the energy in the form of heat. When the same resistor is connected to the dc voltage source and the resistor connected to the ac voltage source and the resistor connected to the dc voltage source generate equal amounts of heat, the effective value of the voltage of the ac voltage source is equal to the value of the voltage of the dc voltage source.
According to the definition of the effective value of the voltage, a plurality of output voltage sampling values V in an alternating current period are obtained according to a certain sampling frequencyiThen, the corresponding effective value V of the output voltage in one AC cycle can be obtained according to the following formularms：
Wherein n is the number of output voltage sampling values obtained by sampling in one alternating current period.
As another embodiment of the present invention, calculating an effective value of an output voltage of an inverter from sampled values of the output voltage may include: acquiring a sampling interval of an output voltage sampling value; determining the output voltage peak value of the inverter according to the maximum value of a plurality of output voltage sampling values in an alternating current period according to the sampling interval; and calculating the effective value of the output voltage of the inverter according to the peak value of the output voltage.
According to the definition of the voltage effective value, the sampling interval of the output voltage sampling value can be set, so that the output voltage sampling value obtained by sampling in an alternating current period contains the peak value of the output voltage, and the output voltage effective value is calculated according to the output voltage peak value.
Optionally, calculating the effective value of the output voltage of the inverter according to the peak value of the output voltage may include: according to
And calculating the effective value of the output voltage of the inverter.
Wherein, VrmsTo output an effective value of voltage, VpIs the output voltage peak.
Optionally, calculating the active power of the inverter according to the output voltage sampled value and the output current sampled value may include: calculating an effective value of the output voltage of the inverter according to a plurality of sampling values of the output voltage in an alternating current period; calculating an effective value of the output current of the inverter according to a plurality of sampling values of the output current in an alternating current period; and calculating the active power of the inverter according to the effective value of the output voltage and the effective value of the output current.
The output voltage effective value can be obtained based on a plurality of output voltage sampling values in an alternating current period, and a sampling interval can also be set, so that the plurality of output voltage sampling values in the alternating current period comprise an output voltage peak value, and the output voltage effective value is obtained according to the output voltage peak value. Similarly, the sum of squares of each output current sample value may be calculated from a plurality of output current sample values in one ac cycle to obtain the sum of squares of the plurality of output current sample values, and the square root of the average of the sums of squares of the plurality of output current sample values may be calculated to obtain the effective value of the output current of the inverter.
Or, the output current sampling value obtained by sampling in one alternating current period is made to include the peak value of the output current according to the sampling interval of the output current sampling value, and the output current effective value is calculated according to the output current peak value.
According to the method for obtaining the effective value of the output current, the effective value of the output voltage and the effective value of the output current in the corresponding alternating current period can be obtained, and further, the active power of the inverter in the corresponding alternating current period is obtained according to the product of the effective value of the output voltage and the effective value of the output current in the corresponding current period.
And step S103, when the effective value and the active power of the output voltage meet a first preset condition and the duration time of the first preset condition is longer than the output undervoltage protection time, triggering undervoltage protection action.
The first preset condition is that the effective value of the output voltage is smaller than the undervoltage protection threshold value and the active power is larger than the power threshold value.
For example, the triggered under-voltage protection action may be switching to a bypass, or other under-voltage protection actions may be set according to the working environment of the inverter, and the specific under-voltage protection action is not limited in this embodiment.
For example, the output under-voltage protection time may be 10ms, or other times set according to the influence of the impact under-voltage condition on the inverter, and the specific output under-voltage protection time is not limited in this embodiment.
In this embodiment, the condition that the inverter triggers the undervoltage protection action is taken as the duration that the output voltage effective value of the inverter is smaller than the undervoltage protection threshold and the active power of the inverter is greater than the power threshold, and the duration that the output voltage effective value of the inverter is smaller than the undervoltage protection threshold and the duration that the active power of the inverter is greater than the power threshold are greater than the output undervoltage protection time, so that the judgment logic of the undervoltage protection of the inverter cannot conflict with the judgment logic of other protections, and further, whether the inverter needs to trigger the undervoltage protection action can be accurately judged, and the reliability of the inverter protection method is improved.
Optionally, the inverter protection method is applied to a scenario where an air switch is disposed between the inverter and the load, and the inverter protection method may further include: and when the output voltage sampling value and the output current sampling value meet a second preset condition, and the duration time of the second preset condition is longer than the short-circuit protection time, triggering a short-circuit protection action to disconnect the air switch.
The second preset condition is that the output voltage sampling value is smaller than the short-circuit protection threshold value and the output current sampling value is larger than the current threshold value.
Wherein the short-circuit protection time is longer than the output undervoltage protection time.
When the output voltage sampling value and the output current sampling value meet a second preset condition and the duration time of the second preset condition is longer than the short-circuit protection time, the short-circuit protection action is triggered to disconnect the air switch, so that the short-circuit current after the short-circuit protection action is triggered to damage other devices of a system where the inverter is located in the protection process of the inverter can be avoided.
Optionally, the short-circuit protection action is triggered to turn off the air switch, and the air switch may be controlled to turn off when the output voltage sampling value and the output current sampling value satisfy a second preset condition, and the duration of the second preset condition is longer than the short-circuit protection time.
Or, the tripping current of the air switch can be set to be less than or equal to the current threshold, and the short-circuit protection time is longer than the time from closing to opening of the air switch. So that when the output voltage sampling value and the output current sampling value meet a second preset condition, and the duration time of the second preset condition is longer than the short-circuit protection time, the air switch is automatically switched off.
The tripping current of the air switch is set to be used for disconnecting the air switch to protect the load when the output current sampling value is larger than the tripping current.
Illustratively, the short-circuit protection time may be 100ms, 200ms or other values, where the short-circuit protection time and the output under-voltage protection time may be in a multiple relationship, for example, 10 times, 20 times, etc., and a specific multiple relationship may be determined by combining the time from closing to opening of the air switch, and the specific value of the short-circuit protection time is not limited in this embodiment.
Optionally, after triggering the short-circuit protection action to disconnect the air switch, the switching may be to the bypass, or other protection actions may be set according to the working environment of the inverter.
In this embodiment, the condition that the inverter triggers the short-circuit protection action is that the output voltage sampling value of the inverter is smaller than the short-circuit protection threshold and the output current sampling value of the inverter is larger than the current threshold, and the duration that the output voltage sampling value of the inverter is smaller than the short-circuit protection threshold and the duration that the output current sampling value of the inverter is larger than the current threshold are larger than the short-circuit protection time. An air switch is arranged between the inverter and the load; the short-circuit protection action is triggered to disconnect the air switch, so that the short-circuit current after the short-circuit protection action is triggered can be prevented from damaging other devices of a system where the inverter is located. The tripping current of the air switch is set to be smaller than or equal to the current threshold, the short-circuit protection time is longer than the time from the closing to the opening of the air switch, and meanwhile, the short-circuit protection time is longer than the output under-voltage protection time, so that the air switch can be automatically opened when a short-circuit working condition occurs, and the short-circuit working condition and the impact under-voltage working condition can be accurately distinguished.
According to the inverter protection method, the condition that the inverter triggers the undervoltage protection action is taken as the condition that the output voltage effective value of the inverter is smaller than the undervoltage protection threshold value, the active power of the inverter is larger than the power threshold value, the duration that the output voltage effective value of the inverter is smaller than the undervoltage protection threshold value and the duration that the active power of the inverter is larger than the power threshold value are larger than the output undervoltage protection time, so that the judgment logic of the undervoltage protection of the inverter can be ensured not to conflict with the judgment logic of other protections, further, whether the inverter needs to trigger the undervoltage protection action or not can be accurately judged, and the reliability of the. The method is characterized in that the conditions that the inverter triggers the short-circuit protection action are taken by setting the output voltage sampling value of the inverter to be smaller than the short-circuit protection threshold value and the output current sampling value of the inverter to be larger than the current threshold value, the duration that the output voltage sampling value of the inverter is smaller than the short-circuit protection threshold value and the duration that the output current sampling value of the inverter is larger than the current threshold value are larger than the short-circuit protection time, the short-circuit protection time is limited to be larger than the output under-voltage protection time, whether the inverter needs to trigger the short-circuit protection action can be accurately judged, the air switch between the inverter and a load is disconnected by limiting the trigger short-circuit protection action, and.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
Fig. 2 shows an exemplary diagram of an inverter protection device provided by the embodiment of the invention, corresponding to the inverter protection method described in the above embodiment. As shown in fig. 2, the apparatus may include: a sampling module 21, a calculation module 22 and a protection module 23.
The sampling module 21 is configured to obtain an output voltage sampling value and an output current sampling value of the inverter;
the calculating module 22 is used for calculating the output voltage effective value of the inverter according to the output voltage sampling value; calculating the active power of the inverter according to the output voltage sampling value and the output current sampling value;
the protection module 23 is configured to trigger an under-voltage protection action when the output voltage effective value and the active power satisfy a first preset condition, and a duration of the first preset condition is longer than an output under-voltage protection time; the first preset condition is that the output voltage effective value is smaller than an undervoltage protection threshold value and the active power is larger than a power threshold value.
Optionally, the protection module 23 is applied to a scenario where an air switch is disposed between the inverter and the load, and may be further configured to trigger a short-circuit protection action to disconnect the air switch when the output voltage sampling value and the output current sampling value satisfy a second preset condition, and a duration of the second preset condition is greater than a short-circuit protection time; the second preset condition is that the output voltage sampling value is smaller than a short-circuit protection threshold value and the output current sampling value is larger than a current threshold value; wherein the short-circuit protection time is greater than the output undervoltage protection time.
Optionally, a trip current of the air switch is less than or equal to the current threshold, and the air switch is turned off to protect the load when the output current sampling value is greater than the trip current; the short-circuit protection time is longer than the time from closing to opening of the air switch.
Optionally, the calculating module 22 may be configured to calculate a sum of squares of each output voltage sample value according to a plurality of output voltage sample values in one ac cycle, so as to obtain a sum of squares of the plurality of output voltage sample values; and calculating the square root of the average value of the square sum of the plurality of output voltage sampling values to obtain the effective value of the output voltage of the inverter.
Optionally, the calculating module 22 may be configured to obtain a sampling interval of the output voltage sampling value; according to the sampling interval, determining the output voltage peak value of the inverter according to the maximum value of a plurality of output voltage sampling values in an alternating current period; and calculating the effective value of the output voltage of the inverter according to the peak value of the output voltage.
Optionally, the calculation module 22 may be used according to
Calculating an effective value of the output voltage of the inverter; wherein, VrmsIs the effective value of the output voltage, VpIs the output voltage peak.
Optionally, the calculating module 22 may be configured to calculate an effective value of the output voltage of the inverter according to a plurality of output voltage sampling values in an ac cycle; calculating an effective value of the output current of the inverter according to a plurality of output current sampling values in an alternating current period; and calculating the active power of the inverter according to the effective value of the output voltage and the effective value of the output current.
According to the inverter protection device, the condition that the inverter triggers the undervoltage protection action is taken as the condition that the output voltage effective value of the inverter is smaller than the undervoltage protection threshold value and the active power of the inverter is larger than the power threshold value, the duration that the output voltage effective value of the inverter is smaller than the undervoltage protection threshold value and the duration that the active power of the inverter is larger than the power threshold value are larger than the output undervoltage protection time, the judgment logic of the undervoltage protection of the inverter can be guaranteed not to conflict with the judgment logic of other protections, and then whether the inverter needs to trigger the undervoltage protection action or not can be accurately judged, and the reliability of the inverter protection. The method is characterized in that the conditions that the inverter triggers the short-circuit protection action are taken by setting the output voltage sampling value of the inverter to be smaller than the short-circuit protection threshold value and the output current sampling value of the inverter to be larger than the current threshold value, the duration that the output voltage sampling value of the inverter is smaller than the short-circuit protection threshold value and the duration that the output current sampling value of the inverter is larger than the current threshold value are larger than the short-circuit protection time, the short-circuit protection time is limited to be larger than the output under-voltage protection time, whether the inverter needs to trigger the short-circuit protection action can be accurately judged, the air switch between the inverter and a load is disconnected by limiting the trigger short-circuit protection action, and.
Fig. 3 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in fig. 3, the terminal device 300 of this embodiment includes: a processor 301, a memory 302 and a computer program 303, such as an inverter protection program, stored in said memory 302 and executable on said processor 301. The processor 301 executes the computer program 303 to implement the steps in the above-described embodiment of the inverter protection method, such as steps S101 to S103 shown in fig. 1, and the processor 301 executes the computer program 303 to implement the functions of the modules in the above-described embodiments of the apparatuses, such as the modules 21 to 23 shown in fig. 2.
Illustratively, the computer program 303 may be divided into one or more program modules that are stored in the memory 302 and executed by the processor 301 to implement the present invention. The one or more program modules may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program 303 in the inverter protection device or terminal equipment 300. For example, the computer program 303 may be divided into the sampling module 21, the calculating module 22 and the protecting module 23, and specific functions of the modules are shown in fig. 2, which is not described in detail herein.
The terminal device 300 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal device may include, but is not limited to, a processor 301, a memory 302. Those skilled in the art will appreciate that fig. 3 is merely an example of a terminal device 300 and does not constitute a limitation of terminal device 300 and may include more or fewer components than shown, or some components may be combined, or different components, for example, the terminal device may also include input output devices, network access devices, buses, etc.
The Processor 301 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 302 may be an internal storage unit of the terminal device 300, such as a hard disk or a memory of the terminal device 300. The memory 302 may also be an external storage device of the terminal device 300, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like, which are provided on the terminal device 300. Further, the memory 302 may also include both an internal storage unit and an external storage device of the terminal device 300. The memory 302 is used for storing the computer programs and other programs and data required by the terminal device 300. The memory 302 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. An inverter protection method, comprising:
acquiring an output voltage sampling value and an output current sampling value of an inverter;
calculating an output voltage effective value of the inverter according to the output voltage sampling value; calculating the active power of the inverter according to the output voltage sampling value and the output current sampling value;
when the output voltage effective value and the active power meet a first preset condition, and the duration time of the first preset condition is longer than the output undervoltage protection time, triggering undervoltage protection action; the first preset condition is that the output voltage effective value is smaller than an undervoltage protection threshold value and the active power is larger than a power threshold value.
2. The inverter protection method according to claim 1, applied to a scenario in which an air switch is provided between the inverter and a load, further comprising:
when the output voltage sampling value and the output current sampling value meet a second preset condition, and the duration time of the second preset condition is longer than the short-circuit protection time, triggering a short-circuit protection action to disconnect the air switch; the second preset condition is that the output voltage sampling value is smaller than a short-circuit protection threshold value and the output current sampling value is larger than a current threshold value;
wherein the short-circuit protection time is greater than the output undervoltage protection time.
3. The inverter protection method of claim 2, wherein a trip current of the air switch is equal to or less than the current threshold value for turning off the air switch to protect the load when the output current sample is greater than the trip current;
the short-circuit protection time is longer than the time from closing to opening of the air switch.
4. The inverter protection method according to any one of claims 1 to 3, wherein the calculating an effective value of the output voltage of the inverter from the sampled value of the output voltage comprises:
calculating the sum of squares of each output voltage sampling value according to a plurality of output voltage sampling values in an alternating current period to obtain the sum of squares of the plurality of output voltage sampling values;
and calculating the square root of the average value of the square sum of the plurality of output voltage sampling values to obtain the effective value of the output voltage of the inverter.
5. The inverter protection method according to any one of claims 1 to 3, wherein the calculating an effective value of the output voltage of the inverter from the sampled value of the output voltage comprises:
acquiring a sampling interval of the output voltage sampling value;
according to the sampling interval, determining the output voltage peak value of the inverter according to the maximum value of a plurality of output voltage sampling values in an alternating current period;
and calculating the effective value of the output voltage of the inverter according to the peak value of the output voltage.
6. The inverter protection method of claim 5, wherein the calculating an effective value of the output voltage of the inverter from the peak value of the output voltage comprises:
according to
Calculating an effective value of the output voltage of the inverter;
wherein, VrmsIs the effective value of the output voltage, VpIs the output voltage peak.
7. The inverter protection method of claim 4, wherein the calculating the active power of the inverter from the sampled output voltage value and the sampled output current value comprises:
calculating an effective value of the output voltage of the inverter according to a plurality of output voltage sampling values in an alternating current period;
calculating an effective value of the output current of the inverter according to a plurality of output current sampling values in an alternating current period;
and calculating the active power of the inverter according to the effective value of the output voltage and the effective value of the output current.
8. An inverter protection device, comprising:
the sampling module is used for acquiring an output voltage sampling value and an output current sampling value of the inverter;
the calculating module is used for calculating the output voltage effective value of the inverter according to the output voltage sampling value; calculating the active power of the inverter according to the output voltage sampling value and the output current sampling value;
the protection module is used for triggering an undervoltage protection action when the output voltage effective value and the active power meet a first preset condition and the duration time of the first preset condition is longer than the output undervoltage protection time; the first preset condition is that the output voltage effective value is smaller than an undervoltage protection threshold value and the active power is larger than a power threshold value.
9. A terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 1 to 7 when executing the computer program.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.
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