CN115249964A - Shutoff device, control method thereof, inverter and photovoltaic power generation system - Google Patents
Shutoff device, control method thereof, inverter and photovoltaic power generation system Download PDFInfo
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- CN115249964A CN115249964A CN202210855467.9A CN202210855467A CN115249964A CN 115249964 A CN115249964 A CN 115249964A CN 202210855467 A CN202210855467 A CN 202210855467A CN 115249964 A CN115249964 A CN 115249964A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/122—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters
- H02H7/1225—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters responsive to internal faults, e.g. shoot-through
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/122—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters
- H02H7/1227—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters responsive to abnormalities in the output circuit, e.g. short circuit
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
- H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
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Abstract
The application discloses a shutoff device and a control method thereof, an inverter and a photovoltaic power generation system, wherein the control method comprises the following steps: acquiring state parameter information of the shutoff device; judging whether the state parameter information accords with a first preset characteristic signal or not; and if the state parameter information accords with a first preset characteristic signal, controlling the shutoff device to be switched off. The method comprises the steps of judging whether state parameter information of the turn-off device accords with a preset characteristic signal or not, and further controlling the turn-off or the turn-on of the turn-off device; the influence on the generated energy during normal power generation operation is reduced, and the resource consumption of the inverter system during normal operation is also reduced.
Description
Technical Field
The application relates to the technical field of photovoltaic power generation, in particular to a shutoff device, a control method of the shutoff device, an inverter and a photovoltaic power generation system.
Background
The photovoltaic power generation technology is an important technology for improving climate and realizing carbon neutralization at present as a renewable energy technology, and is widely applied after the rapid development of over ten years. However, with distributed mass applications, more and more photovoltaic power generation systems are installed on the roofs of residential homes or factory buildings. In order to improve safety, a photovoltaic power generation system is required to be able to be quickly shut down. When a fault condition related to safety occurs, the energy output of the photovoltaic module is quickly cut off through a cut-off device; when the fault is removed and power generation needs to be carried out again, the breaker can recover the energy output of the photovoltaic module.
In the prior art, in order to maintain the continuous output of the energy of the shutdown device, an excitation signal needs to be continuously added to a direct current bus of a photovoltaic system. This not only can lead to the resource consumption of inverter system big, still can lead to the direct current busbar voltage of photovoltaic system can't be accurate in the operation of Maximum Power Point Tracking (MPPT), and then leads to the loss of generated energy.
Disclosure of Invention
The application provides a breaker and a control method thereof, an inverter and a photovoltaic power generation system, and aims to solve the problem that in the prior art, an excitation signal needs to be continuously added to a direct-current bus of the photovoltaic power generation system to maintain the continuous output of energy of the breaker.
One aspect of the present application provides a method for controlling a shutdown device, where the method includes:
acquiring state parameter information of the shutoff device;
judging whether the state parameter information accords with a first preset characteristic signal or not;
and if the state parameter information accords with a first preset characteristic signal, controlling the shutoff device to be switched off.
Another aspect of the present application provides a shutdown device, comprising a controllable switch and a processor;
the controllable switch is connected in series with the anode branch or the cathode branch of the shutoff device;
the processor is configured to acquire state parameter information of the shutdown device; judging whether the state parameter information accords with a first preset characteristic signal or not; and if the state parameter information accords with a first preset characteristic signal, controlling the controllable switch to be switched off.
The application also provides an inverter, wherein a positive electrode input end of the inverter is connected with a positive electrode output end of one breaker or positive electrode output ends after n breakers are cascaded through a positive direct current bus, and a negative electrode input end of the inverter is connected with a negative electrode output end of one breaker or negative electrode output ends after n breakers are cascaded through a negative direct current bus; the inverter includes a controller;
the controller is configured to control an input voltage of the inverter to generate a characteristic pulse signal for controlling the one or the n turn-off devices to be turned on or off.
The present application also provides a photovoltaic power generation system, which comprises at least one said shutoff device and at least one said inverter.
According to the shutdown device and the control method thereof, the inverter and the photovoltaic power generation system, the shutdown device is controlled to be turned off by judging whether the state parameter information of the shutdown device meets the preset characteristic signal; the influence on the generated energy during normal power generation operation is reduced, and the resource consumption of the inverter system during normal operation is also reduced.
Drawings
Fig. 1 is a schematic view of a photovoltaic power generation system according to an embodiment of the present application;
FIG. 2 is a schematic view of another photovoltaic power generation system provided in an embodiment of the present application;
FIG. 3 is a schematic view of another photovoltaic power generation system provided by an embodiment of the present application;
FIG. 4 is a schematic diagram of a shutdown device provided in an embodiment of the present application;
FIG. 5 is a schematic diagram of a first predetermined characteristic signal provided in an embodiment of the present application;
FIG. 6 is a schematic diagram of a second predetermined characteristic signal provided in an embodiment of the present application;
FIG. 7 is a schematic diagram of another second predetermined characteristic signal provided in an embodiment of the present application;
FIG. 8 is a schematic diagram of the modified first predetermined signature of FIG. 5;
fig. 9 is a schematic diagram of PV and IV curves of a photovoltaic module provided by an embodiment of the present application;
FIG. 10 is a schematic diagram of a second modified pre-defined signature signal of FIG. 6;
FIG. 11 is a schematic diagram of a second modified pre-defined signature signal of FIG. 7;
fig. 12 is a schematic flowchart of a control method of a shutdown device according to an embodiment of the present application;
fig. 13 is a schematic diagram of a control process of a shutdown device according to an embodiment of the present application;
FIG. 14 is a schematic diagram of a self-test process of a shutoff device according to an embodiment of the present application;
fig. 15 is a schematic diagram of another control process of the shutdown device according to the embodiment of the present application.
The implementation, functional features and advantages of the objectives of the present application will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer and clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of and not restrictive on the broad application.
In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Fig. 1 is a schematic view of a photovoltaic power generation system according to an embodiment of the present disclosure.
As shown in fig. 1, the photovoltaic power generation system includes n photovoltaic modules, n shutdown devices, and an inverter.
The input ends of the n shut-off devices are connected with the output ends of the n photovoltaic modules in a one-to-one correspondence manner, the output ends of the n shut-off devices are cascaded, the cascaded positive electrode output end is connected with the positive electrode input end of the inverter through a positive direct current bus, and the cascaded negative electrode output end is connected with the negative electrode input end of the inverter through a negative direct current bus.
The inverter comprises a first booster circuit (shown by a dotted line frame in the figure, the booster circuit is also called a Boost circuit), the first booster circuit performs Maximum Power Point Tracking (MPPT) on the voltage between the positive direct current bus and the negative direct current bus, and the inverter is connected with an alternating current power grid after inversion.
Fig. 2 is a schematic view of another photovoltaic power generation system provided in an embodiment of the present application.
In contrast to the example of fig. 1, the photovoltaic power generation system includes 2n photovoltaic modules, and the input of each shutdown device is connected to 2 photovoltaic modules.
Fig. 3 is a schematic view of another photovoltaic power generation system provided in the embodiments of the present application.
Different from the example of fig. 1, the photovoltaic power generation system further includes m photovoltaic modules and m shutdown devices, wherein input ends of the m shutdown devices are connected with output ends of the m photovoltaic modules in a one-to-one correspondence manner, output ends of the m shutdown devices are cascaded, a positive output end after the cascade connection is connected with a positive input end of the inverter through another positive direct current bus, and a negative output end after the cascade connection is connected with a negative input end of the inverter through another negative direct current bus.
The inverter further comprises a second booster circuit (shown by a dashed line frame in the figure), the second booster circuit performs Maximum Power Point Tracking (MPPT) on the voltage between the other positive direct-current bus and the other negative direct-current bus, and the second booster circuit is connected with the alternating-current power grid after being inverted by the inverter.
Fig. 4 is a schematic diagram of a shutdown device according to an embodiment of the present disclosure.
As shown in fig. 4, the turn-off device includes a controllable switch K1, a bypass diode D2, a driving unit, an input voltage sampling unit, an output voltage sampling unit, a temperature detection unit, an output current sampling unit, a processor, an auxiliary power supply, an output voltage regulator Vdc, and an anti-reverse diode D1.
The controllable switch K1 is arranged on the anode branch or the cathode branch of the turn-off device. In the figure, vin is an input voltage of the turn-off device, vo is an output voltage of the turn-off device, and reference may be made to the aforementioned photovoltaic power generation system for connection relationship between the positive input/output end or the negative input/output end of the turn-off device, the photovoltaic module, and the inverter.
The output end of the processor is connected with the control end of the controllable switch K1 through the driving unit, and the processor outputs a control signal to drive the controllable switch K1 to be switched on or switched off through the driving unit, so that the switching-on or switching-off of the switching-off device is realized.
And the bypass diode D2 is used for realizing the bypass output of the turn-off device when the turn-off device is turned off.
The state parameters of the shut-off device comprise input voltage, output voltage, temperature and output current, and the parameters can reflect the state of the shut-off device; the output current refers to the output current of the channel without the bypass diode D2 inside. The input voltage, the output voltage, the temperature and the output current are respectively realized through an input voltage sampling unit, an output voltage sampling unit, a temperature detection unit and an output current sampling unit, and the units form a state parameter acquisition unit of the shutoff device.
The power of the auxiliary power supply is from the input of the cut-off device, namely the output voltage of the photovoltaic module; one path of the auxiliary power supply outputs auxiliary power supply (such as power supply of a processor in the figure) for the breaker, the other path generates an output stabilized voltage power supply Vdc, one end of the output stabilized voltage power supply Vdc is connected with the negative electrode output end of the breaker, and the other end of the output stabilized voltage power supply Vdc is connected with the positive electrode output end of the breaker through an anti-reverse diode D1.
It should be noted that in other examples, it is also possible that the driving unit is integrated in the processor. Other bypass circuit implementations of the bypass diode D2 are also possible. Other implementations of the anti-reverse diode D1 using other anti-reverse circuits are also possible.
In an example, the processor is configured to obtain status parameter information of the shutdown device; judging whether the state parameter information accords with a first preset characteristic signal or not; the first preset characteristic signal is used for marking a signal which needs to turn off the turn-off device; and if the state parameter information conforms to a first preset characteristic signal, controlling the controllable switch K1 to be switched off.
Taking the state parameter as the output voltage Vc of the stabilized voltage supply as an example:
generally, the area of a photovoltaic power generation system is relatively large, although a direct-current bus branch system corresponding to a shutdown device does not have a safety fault, other branch systems in the same region may have safety faults, or when maintenance personnel need to overhaul a photovoltaic module in the region, a command needs to be sent to the shutdown device at the moment to inform the shutdown device to shut down, so that the shutdown device stops energy and voltage output. In the conventional scheme, an inverter or a special transmitting device generally transmits a command through a power carrier or other wireless communication schemes, and a shutdown device receives the command and executes the command, so that a set of command transmitting and receiving devices are necessarily required, and extra cost is increased regardless of the power carrier or the special wireless transmitting and receiving device.
In this example, when the system needs to be overhauled or other branch systems in the same area have a safety fault, a switching tube in a boost circuit of the inverter may be controlled, so that the output voltage Vc of the regulated power supply generates a periodic characteristic pulse signal, and the shutoff device performs a corresponding shutoff or on operation when detecting the signal.
For example, in the switching tubes Q1 and Q2 shown in fig. 3, if the switching tube Q1 and the switching tube Q2 are constantly on, the corresponding dc bus is short-circuited, and at this time, the output regulated power Vdc is also short-circuited; if the constant conducting signals of the switching tube Q1 and the switching tube Q2 disappear, the corresponding direct current bus returns to be normal, at the moment, the anti-reverse diode D1 is cut off, and the voltage Vc of the output stabilized voltage power supply is equal to the voltage of the output stabilized voltage power supply Vdc. Thus, through the control of the switching tube Q1 and the switching tube Q2 (which can be realized by the controller of the inverter), the output stabilized voltage Vc can generate a periodic characteristic pulse signal.
And if the periodic characteristic pulse signal generated by the voltage Vc of the output stabilized voltage supply conforms to a first preset characteristic signal, controlling the controllable switch K1 to be switched off.
As shown in fig. 5, it is assumed that the first predetermined characteristic signal includes a pulse width modulation signal lasting for one or more periods, in each of which the high level signal has a duration (time length) of T1, the low level signal has a duration of T2, and T1 is smaller than T2. If the detected voltage Vc of the output stabilized voltage supply contains a pulse width modulation signal lasting for one or more periods, the periodic characteristic pulse signal generated by the voltage Vc of the output stabilized voltage supply can be determined to accord with a first preset characteristic signal, and at the moment, the controllable switch K1 is controlled to be switched off to stop energy and voltage output.
It should be noted that, the above-mentioned "the output regulated voltage Vc contains a pulse width modulation signal lasting for one or more cycles" may be a case where the output regulated voltage Vc contains a pulse width modulation signal lasting for one cycle, and the first preset characteristic signal is a pulse width modulation signal lasting for one or more cycles; the output voltage Vc of the regulated power supply may include a pwm signal lasting for a plurality of cycles, and the first preset characteristic signal may also be a pwm signal lasting for a plurality of cycles, where the number of cycles in the two may be the same or different, for example: the output stabilized voltage Vc contains a pulse width modulation signal lasting for 3 periods, and the first preset characteristic signal is a pulse width modulation signal lasting for 4 periods; alternatively, the output regulated voltage Vc comprises a pwm signal lasting 4 cycles, and the first predetermined characteristic signal is a pwm signal lasting 3 cycles.
It should be noted that, in other examples, whether the periodic characteristic pulse signal generated by the voltage Vc of the regulated power supply meets the first preset characteristic signal may be determined by comparing a certain parameter in the pwm signal or a parameter derived from the certain parameter. For example: if the detected output regulated voltage Vc contains a low level signal whose duration is equal to T2 (or greater than T2), it is determined that the periodic characteristic pulse signal generated by the output regulated voltage Vc conforms to the first preset characteristic signal. The duration of the high-level signal may also be relatively high, that is, if the detected output regulated voltage Vc contains a high-level signal whose duration is equal to T1 (or greater than T1), it may be determined that the periodic characteristic pulse signal generated by the output regulated voltage Vc conforms to the first preset characteristic signal. Duty cycles, etc. may also be compared.
In one embodiment, to prevent the turn-off device from being turned on by mistake, it can be determined whether the duration of the periodic characteristic pulse signal generated by the output regulated voltage Vc does not meet the duration of the first preset characteristic signal and exceeds a preset duration threshold T3 (which may be greater than T3, or greater than or equal to T3). And if the preset duration threshold value T3 is exceeded, controlling the on-off device to be switched on.
In the above process, in order to prevent the output regulated power Vdc from being damaged or from pulling across the auxiliary power supply of the shutdown device, a current limiting resistor is generally connected in series during the design.
In the above process, in order to transmit information that the system has a safety fault or needs to be overhauled, the switching tube in the boost circuit of the inverter is controlled to output the periodic characteristic pulse signal generated by the voltage Vc of the stabilized voltage power supply, and in practice, the characteristic pulse signal (or the first preset characteristic signal) can also be directly set to be a constant low level signal with a certain time length. Thus, the output voltage Vo of the turn-off device is directly pulled down, and the auxiliary power supply is powered off and the drive of the controllable switch K1 is powered off and disconnected. When the photovoltaic module is restarted after being disconnected, if the photovoltaic module is in a default disconnection state, the shutdown device can be controlled to be switched on only when the processor of the shutdown device detects that the voltage Vc of the output stabilized voltage power supply is recovered to be normal, and therefore the energy of the corresponding photovoltaic module is output.
It should be noted that the above examples show two different embodiments of the first predetermined characteristic signal (one is a constant low level signal with a certain time length, and the other is a pulse width modulation signal lasting for one or more periods). It is conceivable, but not limited to, these two ways. For example: slightly changing the pwm signal shown in fig. 5, in the first period, the duration (time length) of the high level signal is T1, the duration of the low level signal is T2, and T1 is less than T2; however, in the second period, the duration (time length) of the high level signal is T2, the duration of the low level signal is T1, and T1 is smaller than T2; the foregoing two cycle variation is then repeated.
In another implementation, if the periodic characteristic pulse signal generated by the output stabilized voltage supply voltage Vc does not conform to the first preset characteristic signal, it is continuously determined whether the periodic characteristic pulse signal generated by the output stabilized voltage supply voltage Vc conforms to the second preset characteristic signal; the second preset characteristic signal is used for marking a signal which needs to turn on the turn-off device; and if the periodic characteristic pulse signal generated by the voltage Vc of the output stabilized voltage supply accords with the second preset characteristic signal, controlling the on-off of the shutoff device.
In order to facilitate the component to recognize the difference between the first predetermined characteristic signal and the second predetermined characteristic signal, it may be defined that the pulse duty cycle and/or the pulse period of the second predetermined characteristic signal is not consistent with the first predetermined characteristic signal (assuming that the second predetermined characteristic signal is also a pulse width modulation signal).
As shown in fig. 6, if the pulse duty ratios are not consistent, the high level time T1 and the low level time T2 of each period of the pulse signal are set differently, for example, T1 of the first preset characteristic signal may be greater than T2, but T1 of the second preset characteristic signal may be less than T2; conversely, the first predetermined characteristic signal T1 may be smaller than T2, but the second predetermined characteristic signal T1 is larger than T2.
As shown in fig. 7, if the pulse periods do not coincide, the high time T1 plus the low time T2 of each period of the pulse signal may be made to coincide with the total period of the first preset characteristic signal.
In the above determination process, if the periodic characteristic pulse signal generated by the output regulated voltage Vc does not conform to the first preset characteristic signal or the second preset characteristic signal, the state of the shutdown device may be maintained unchanged, i.e., the existing shutdown or on state is not changed.
Taking the state parameter as the output voltage Vo of the turn-off device as an example:
in the example of fig. 5, a voltage value corresponding to a low-level signal of the first preset characteristic signal is close to 0, so that when the low-level signal is detected, both input and output voltages of the shutdown device are relatively low, and a certain measure needs to be taken to ensure that an auxiliary power supply of the shutdown device is not powered down, otherwise, when the inverter controls the dc bus to generate a specific periodic characteristic pulse signal, because the input of the shutdown device is also pulled low by a short circuit, the auxiliary power supply is not provided, the output of the shutdown device is directly turned off, and thus, when the self-test of the shutdown device needs to be started again, the shutdown device may be unable to be woken up.
To avoid this, as shown in fig. 8, the low level signal of the first preset characteristic signal is controlled by the MPPT circuit of the inverter to be between one third of the normal operation voltage before the fault and two thirds of the normal operation voltage before the fault, and preferably to be one half of the normal operation voltage before the fault.
Specifically, when the inverter detects that safety fault information exists or potential safety hazards exist when superior monitoring information is received or a maintenance worker needs to inspect a photovoltaic region and has safety risks, the inverter changes operation logic of all input MPPT circuits. During a period of time T1, the Boost circuit of the inverter operates in a Maximum Power Point Tracking (MPPT) state, such as a PV curve shown in fig. 9, i.e., a point a in the figure. And in a period of time T2, controlling the Boost circuit to work at a point B in the graph, namely actively abandoning the MPPT, and enabling the Boost circuit of each path of MPPT to enter a constant input voltage operation state, wherein the input voltage is reduced to a half of the period of time T1. Similarly, when the processor detects that the output voltage Vo meets the first preset characteristic signal shown in fig. 8, the processor controls the controllable switch K1 to be turned off.
Similarly to the above, the second predetermined characteristic signal may also be so set. In particular, reference may be made to the schematic illustrations of fig. 10-11.
In an example, the state parameter includes an output current of the shut-off;
the processor is configured to judge whether the output current of the turn-off device contains arc discharge information; and if the output current of the turn-off device contains arc-pulling information, controlling the turn-off device to turn off.
If the arc discharge phenomenon exists in the photovoltaic power generation system, personal danger and fire accidents can be caused. Therefore, when the arc discharge phenomenon occurs, the controllable switch K1 needs to be controlled to be turned off.
In an example, the status parameter includes a temperature within the shutdown device;
the processor is configured to determine whether the temperature within the shutdown device exceeds a preset temperature threshold; and if the temperature in the shutoff device exceeds a preset temperature threshold value, controlling the shutoff device to be turned off.
When the temperature in the shutoff device is over-temperature, high-temperature fire risks exist. Therefore, it is necessary to control the controllable switch K1 to be turned off.
In an example, the state parameters include an output current and an output voltage of the shut-off;
the processor is configured to determine whether the output current of the shut-off device is higher than a preset current threshold and the output voltage of the shut-off device is lower than a preset voltage threshold; and if the output current of the turn-off device is greater than a preset current threshold value and the output voltage of the turn-off device is lower than a preset voltage threshold value, controlling the turn-off device to turn off.
In general, the photovoltaic module operates in a Maximum Power Point Tracking (MPPT) state, but when the output end of the shutdown device shown in fig. 4 has a short-circuit fault, which is equivalent to an output short-circuit of the input photovoltaic module, referring to the PV curve and the IV curve graph of the photovoltaic module shown in fig. 9, it can be known that the photovoltaic module enters a short-circuit operating region: the output current is large but the voltage is low. The short circuit at the output end of the cut-off device can be a short circuit of a positive direct current bus and a negative direct current bus in a photovoltaic power generation system caused by cable crust breaking, a short circuit of the positive direct current bus and the negative direct current bus caused by heat of a direct current input end of an inverter such as MC4 hair, a short circuit of the positive direct current bus and the negative direct current bus caused by damage of devices inside the inverter, and the like. Therefore, whether the direct current bus of the system has a short circuit safety fault can be judged according to the characteristics of large current and low voltage. Specifically, it is determined whether the output current of the turn-off unit is higher than a preset current threshold (may be greater than or equal to, or may be greater than), and whether the output voltage is lower than a preset voltage threshold (may be less than or equal to, or may be less than), and if both the output voltage and the output current are satisfied, the controllable switch K1 is controlled to turn off, so that the module stops outputting energy and voltage. In this example, the output current refers to an output current without the bypass diode D2 inside. The preset current threshold may be defined as 50% of the rated current of the photovoltaic module under standard test conditions, i.e. if the rated current parameter of the photovoltaic module is 18A, the preset current threshold may be 9A. The preset voltage threshold may be defined as 40% of the open circuit voltage of the photovoltaic module, i.e. if the open circuit voltage is 50V under standard test conditions of the photovoltaic module, the preset voltage threshold may be taken as 20V. Thus, when the current is detected to be higher than 9A and the voltage is detected to be lower than 20V, the condition that the output is short-circuited can be considered.
Fig. 12 is a schematic flowchart of a method for controlling a shutdown device according to an embodiment of the present disclosure.
As shown in fig. 12, the control method includes:
step S11, acquiring state parameter information of the shutoff device;
s12, judging whether the state parameter information accords with a first preset characteristic signal;
and S13, if the state parameter information accords with a first preset characteristic signal, controlling the shutoff device to be turned off.
The first preset characteristic signal is set to facilitate the recognition and comparison of the processor of the shutdown device, so as to facilitate the judgment and control of the shutdown device to be turned off.
In one example, the state parameter comprises an output voltage of the shut-off or an output regulated supply voltage internal to the shut-off.
Wherein the state parameter information includes the output voltage or the output regulated power supply voltage for a duration of time.
In an example, the first preset characteristic signal comprises a constant level signal having a preset time length;
if the state parameter information contains the constant level signal and the time length of the constant level signal exceeds the preset time length, the state parameter information conforms to the first preset characteristic signal; otherwise, the state parameter information does not conform to the first preset characteristic signal.
In an example, the first preset characteristic signal comprises a pulse width modulated signal lasting one or more cycles;
if the state parameter information contains a pulse width modulation signal lasting for one or more periods, the state parameter information conforms to the first preset characteristic signal; otherwise, the state parameter information does not conform to the first preset characteristic signal.
In one example, the voltage value corresponding to the low-level signal in the pulse width modulation signal is between one third of the voltage value corresponding to the high-level signal and two thirds of the voltage value corresponding to the high-level signal.
In one example, the determining whether the state parameter information conforms to a first preset characteristic signal further includes:
and if the duration time of the state parameter information which does not accord with the first preset characteristic signal exceeds a preset duration time threshold, controlling the on-off device to be switched on.
In an example, the determining whether the state parameter information conforms to a first preset characteristic signal further includes:
if the state parameter information does not accord with a first preset characteristic signal, judging whether the state parameter information accords with a second preset characteristic signal or not;
and if the state parameter information accords with the second preset characteristic signal, controlling the on-off of the shutoff device.
In an example, the duty cycle and/or period of the second predetermined characteristic signal is different from the first predetermined characteristic signal.
In an example, the state parameter comprises an output current of the shut-off;
after the obtaining of the state parameter information of the shutdown device, the method further includes:
judging whether the output current of the breaker contains arc discharge information or not;
and if the output current of the turn-off device contains arc-pulling information, controlling the turn-off device to turn off.
In an example, the status parameter includes a temperature within the shutdown device;
after the obtaining the state parameter information of the shutdown device, the method further comprises:
judging whether the temperature in the shutoff device exceeds a preset temperature threshold value or not;
and if the temperature in the shutoff device exceeds a preset temperature threshold value, controlling the shutoff device to be turned off.
In an example, the state parameters include an output current and an output voltage of the shut-off;
after the obtaining of the state parameter information of the shutdown device, the method further includes:
judging whether the output current of the turn-off device is higher than a preset current threshold value and whether the output voltage of the turn-off device is lower than a preset voltage threshold value;
and if the output current of the turn-off device is greater than a preset current threshold value and the output voltage of the turn-off device is lower than a preset voltage threshold value, controlling the turn-off device to be turned off.
The control process of the shutdown device is explained below with reference to fig. 13 to 14:
as shown in fig. 13, after a shutdown device in a photovoltaic power generation system is first powered on, an output of a default shutdown device is initialized, and then a self-test is started: namely, the state parameter information of the shutdown device is detected, and whether the shutdown device has safety fault information or not is judged. Specifically, the self-test process can refer to fig. 14:
firstly, judging whether the output current of the turn-off device contains arc discharge information or not; and if the output current of the turn-off device contains arc pulling information, setting a turn-off mark of the turn-off device and controlling the turn-off of the turn-off device.
If the output current of the turn-off device does not contain arc-pulling information, judging whether the temperature in the turn-off device exceeds a preset temperature threshold value or not; and if the temperature in the shutoff device exceeds a preset temperature threshold value, setting a shutoff mark of the shutoff device and controlling the shutoff device to be turned off.
If the temperature in the shutdown device does not exceed the preset temperature threshold, determining whether the voltage Vc of the output voltage-stabilized power supply is pulled low by a short circuit (refer to fig. 4 and the corresponding description thereof); if the voltage Vc of the output stabilized voltage supply is pulled low by a short circuit, the direct current bus has a short-circuit safety fault, and a shutoff mark of a shutoff device is set to control the shutoff device to be turned off.
If the voltage Vc of the output stabilized voltage supply is not pulled down by a short circuit, judging whether the output current of the breaker is higher than a preset current threshold value or not and whether the output voltage of the breaker is lower than a preset voltage threshold value or not; and if the output current of the turn-off device is higher than a preset current threshold value and the output voltage of the turn-off device is lower than a preset voltage threshold value, setting a turn-off mark of the turn-off device and controlling the turn-off of the turn-off device.
When it is determined that the shutdown device itself has no safety fault information through the self-checking process, the output voltage Vo of the shutdown device is detected, and whether the output voltage Vo of the shutdown device meets the first preset characteristic signal is determined (refer to fig. 5 and the corresponding description).
And if the output voltage Vo of the turn-off device accords with the first preset characteristic signal, setting a turn-off mark of the turn-off device and controlling the turn-off of the turn-off device. And if the duration time that the output voltage Vo of the turn-off device does not accord with the first preset characteristic signal exceeds a preset duration time threshold value, turning on a turn-on mark of the turn-off device to control the turn-on of the turn-off device.
Fig. 15 is a schematic diagram of another control process of the shutdown device according to the embodiment of the present application.
In contrast to the example of fig. 13, if the output voltage Vo of the shutdown device does not meet the first preset characteristic signal, it is continuously determined whether the output voltage Vo of the shutdown device meets the second preset characteristic signal. And if the output voltage Vo of the turn-off device accords with the second preset characteristic signal, setting a turn-on mark of the turn-off device and controlling the turn-on of the turn-off device. If the output voltage Vo of the turn-off device does not meet the second predetermined characteristic signal, the state of the turn-off device is maintained, i.e., the existing turn-off or turn-on state is not changed.
The preferred embodiments of the present application have been described above with reference to the accompanying drawings, and the scope of the claims of the present application is not limited thereby. Any modifications, equivalents and improvements which may occur to those skilled in the art without departing from the scope and spirit of the present application are intended to be within the scope of the claims of the present application.
Claims (16)
1. A method of controlling a shutdown device, the method comprising:
acquiring state parameter information of the shutoff device;
judging whether the state parameter information accords with a first preset characteristic signal or not;
and if the state parameter information accords with a first preset characteristic signal, controlling the shutoff device to be switched off.
2. The control method of claim 1, wherein the state parameter comprises an output voltage of the shut-off or an output regulated voltage inside the shut-off.
3. The control method according to claim 1, wherein the first preset feature signal includes a constant level signal having a preset time length;
if the state parameter information contains the constant level signal and the time length of the constant level signal exceeds the preset time length, the state parameter information conforms to the first preset characteristic signal; otherwise, the state parameter information does not conform to the first preset characteristic signal.
4. The control method of claim 1, wherein the first preset characteristic signal comprises a pulse width modulated signal lasting one or more cycles;
if the state parameter information contains a pulse width modulation signal lasting for one or more periods, the state parameter information conforms to the first preset characteristic signal; otherwise, the state parameter information does not conform to the first preset characteristic signal.
5. The control method according to claim 4, wherein the voltage value corresponding to the low level signal in the PWM signal is between one third of the voltage value corresponding to the high level signal and two thirds of the voltage value corresponding to the high level signal.
6. The control method according to claim 1, wherein said determining whether the state parameter information conforms to a first predetermined characteristic signal further comprises:
and if the duration time of the state parameter information which does not conform to the first preset characteristic signal exceeds a preset duration time threshold, controlling the on-off device to be switched on.
7. The control method according to claim 1, wherein said determining whether the state parameter information conforms to a first predetermined characteristic signal further comprises:
if the state parameter information does not accord with a first preset characteristic signal, judging whether the state parameter information accords with a second preset characteristic signal;
and if the state parameter information accords with the second preset characteristic signal, controlling the on-off of the shutoff device.
8. Control method according to claim 7, characterized in that the duty cycle and/or the period of the second preset characteristic signal is different from the first preset characteristic signal.
9. The control method according to claim 1, wherein the state parameter includes an output current of the shut-off device;
after the obtaining of the state parameter information of the shutdown device, the method further includes:
judging whether the output current of the breaker contains arc discharge information or not;
and if the output current of the turn-off device contains arc-pulling information, controlling the turn-off device to turn off.
10. The control method according to claim 1, characterized in that the status parameter comprises a temperature inside the shutoff;
after the obtaining of the state parameter information of the shutdown device, the method further includes:
judging whether the temperature in the shutoff device exceeds a preset temperature threshold value or not;
and if the temperature in the shutoff device exceeds a preset temperature threshold value, controlling the shutoff device to be turned off.
11. The control method according to claim 1, wherein the state parameters include an output current and an output voltage of the shut-off device;
after the obtaining of the state parameter information of the shutdown device, the method further includes:
judging whether the output current of the turn-off device is higher than a preset current threshold value and whether the output voltage of the turn-off device is lower than a preset voltage threshold value;
and if the output current of the turn-off device is greater than a preset current threshold value and the output voltage of the turn-off device is lower than a preset voltage threshold value, controlling the turn-off device to turn off.
12. A shutoff device is characterized by comprising a controllable switch and a processor;
the controllable switch is connected in series with the anode branch or the cathode branch of the shutoff device;
the processor is configured to acquire state parameter information of the shutoff device; judging whether the state parameter information accords with a first preset characteristic signal or not; and if the state parameter information accords with a first preset characteristic signal, controlling the controllable switch to be switched off.
13. The gate breaker of claim 12, further comprising a state parameter collecting unit for collecting state parameter information of the gate breaker.
14. The shutdown device of claim 12, further comprising an auxiliary power supply, an output regulated power supply, and a deboost circuit;
the power of the auxiliary power supply is from the input of the shutoff device; one path of output of the auxiliary power supply is used for auxiliary power supply of the processor, and the other path of the auxiliary power supply generates an output stabilized voltage power supply;
one end of the output voltage-stabilized power supply is connected with the negative pole branch of the breaker, and the other end of the output voltage-stabilized power supply is connected with the positive pole branch of the breaker through the anti-reverse circuit.
15. An anode input end of the inverter is connected with an anode output end of a breaker or anode output ends after n breakers are cascaded through a positive direct current bus, and a cathode input end of the inverter is connected with a cathode output end of a breaker or cathode output ends after n breakers are cascaded through a negative direct current bus; characterized in that the inverter comprises a controller;
the controller is configured to control an input voltage of the inverter to generate a characteristic pulse signal for controlling the one or the n turn-off devices to be turned on or off.
16. A photovoltaic power generation system, characterized by comprising at least one shut-off device according to any one of claims 12-14 and at least one inverter according to claim 15.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115632389A (en) * | 2022-12-22 | 2023-01-20 | 杭州禾迈电力电子股份有限公司 | Shutoff device, control method thereof and photovoltaic power generation system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115632389A (en) * | 2022-12-22 | 2023-01-20 | 杭州禾迈电力电子股份有限公司 | Shutoff device, control method thereof and photovoltaic power generation system |
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