CN117767708A

CN117767708A - Control method and circuit of controllable switch

Info

Publication number: CN117767708A
Application number: CN202311812729.4A
Authority: CN
Inventors: 杨宗军; 柏杨; 李晓迅
Original assignee: Sungrow Power Supply Co Ltd
Current assignee: Sungrow Power Supply Co Ltd
Priority date: 2023-12-25
Filing date: 2023-12-25
Publication date: 2024-03-26

Abstract

The invention provides a control method and a circuit of a controllable switch, which are applicable to a power converter connected to a power grid, wherein the power converter at least comprises the controllable switch and a controller, and the method comprises the following steps: when the controllable switch is in an off state, acquiring power grid parameters of a power grid connected with an output end of the controllable switch in real time; when the power grid parameters reach the appointed trigger value of the last-time closing instruction, the controllable switch is controlled to be closed; the designated trigger value of the last issued closing instruction is determined according to an impact signal generated by the input end and/or the output end of the controllable switch in the closing process of the controllable switch. In the scheme, in the process of changing the controllable switch from the open state to the closed state every time, the appointed trigger value of the next issuing closing instruction is continuously corrected by utilizing the impact signal of any end of the controllable switch detected in real time, so that the controllable switch is ensured to be close to the real voltage zero crossing point every time when being closed, the impact is reduced, and the service life of the controllable switch is prolonged.

Description

Control method and circuit of controllable switch

Technical Field

The invention relates to the technical field of relays, in particular to a control method and a circuit of a controllable switch.

Background

In the new energy industry, when energy sources such as photovoltaic, wind power and energy storage are connected to a power grid through a power converter, controllable switches with obvious disconnection nodes, such as relays and circuit breakers, are required to be connected, so that equipment can be safely disconnected from the power grid under abnormal conditions. Fig. 1 shows a schematic diagram of a typical application scenario of a controllable switch, wherein the left side is a converter or other grid load, and the right side is a grid. In the application scenario shown in fig. 1, the controllable switch is directly closed, and the port capacitor is usually charged instantaneously due to the pressure difference between two ends of the controllable switch, so that larger impulse voltage and current are easily generated, thereby affecting the service life of the controllable switch contact.

In the prior art, a method of detecting a zero crossing point of a current at the grid side of a controllable switch is generally adopted, and under the condition of compensating a constant action delay Ts of the controllable switch (action time Ts: sending a control signal to the controllable switch, a period of time is needed to pass before the controllable switch is responded and closed, and the period of time is the action time Ts of the controllable switch), the method of connecting two ends at the zero crossing point is realized as much as possible, so that larger impulse voltage and current are avoided. However, the method has poor applicability because the types of the controllable switches are different and the corresponding action time Ts is also different.

Therefore, a switch control scheme with high applicability is needed at present, so that the controllable switch is close to the real voltage zero crossing point as much as possible when being closed, the impact is reduced, and the service life of the controllable switch is prolonged.

Disclosure of Invention

Therefore, the embodiment of the invention provides a control method and a circuit of a controllable switch, so as to achieve the purposes of enabling the controllable switch to be close to a real voltage zero crossing point as much as possible, reducing impact and prolonging the service life of the controllable switch.

In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:

the embodiment of the invention discloses a control method of a controllable switch, which is suitable for a power converter connected to a power grid, wherein the power converter at least comprises the controllable switch and a controller, and the method comprises the following steps:

when the controllable switch is in an off state, the controller acquires power grid parameters of a power grid connected with the output end of the controllable switch in real time;

when the power grid parameter reaches a designated trigger value which is determined at the previous time and transmits a closing instruction, controlling the controllable switch to be closed;

the designated trigger value of the last determined closing command is obtained by correcting the designated trigger value of the closing command based on the impact signal when the impact signal generated by the input end and/or the output end of the controllable switch is detected in real time in the process of controlling the controllable switch to be changed from the open state to the closed state in the last time.

Optionally, the power grid parameter includes a phase, and the specified trigger value is a specified phase;

when the controllable switch is in an off state, acquiring the power grid parameters of a power grid connected with the output end of the controllable switch in real time, wherein the method comprises the following steps:

when the controllable switch is in an off state, acquiring the voltage of a power grid connected with the output end of the controllable switch in real time;

calculating the voltage of the power grid based on a phase-locked loop to obtain the phase of the power grid;

correspondingly, when the power grid parameter reaches a designated trigger value which is determined in the last time and issues a closing instruction, the controllable switch is controlled to be closed, and the method comprises the following steps:

and when the phase of the power grid reaches the designated phase of the last determined issuing of the closing instruction, controlling the controllable switch to be closed.

Optionally, the power grid parameter includes a voltage, and the specified trigger value is a specified voltage;

And when the voltage of the power grid reaches the designated voltage which is determined before and sends a closing instruction, controlling the controllable switch to be closed.

Optionally, in the process of closing the controllable switch, the method further includes:

detecting whether the input end and/or the output end of the controllable switch generate a voltage impact signal or not in real time or generate a current impact signal;

if the input end and/or the output end of the controllable switch generate a voltage impact signal or generate a current impact signal, correcting the designated trigger value of the last determined issuing closing instruction based on the voltage impact signal or the current impact signal to obtain the designated trigger value of the next issuing closing instruction;

if the input end and the output end of the controllable switch do not generate voltage impact signals or do not generate current impact signals, continuing to use the designated trigger value of the last determined closing instruction to be issued as the designated trigger value of the next closing instruction.

Optionally, if the specified trigger value is a specified phase, correcting the specified trigger value of the last determined issued closing instruction based on the voltage impact signal to obtain the specified trigger value of the next issued closing instruction, including:

Determining the generation time of the voltage impact signal;

determining the issuing time of the closing instruction according to the designated phase of the issuing closing instruction determined in the previous time;

calculating the actual closing time of the controllable switch according to the issuing time of the closing instruction and the generating time of the voltage impact signal;

calculating to obtain a phase change value according to the actual closing time of the controllable switch and the period of the power grid;

and correcting the designated phase of the last determined issued closing instruction by using the phase change value to obtain a designated trigger value of the next issued closing instruction.

determining the polarity of the voltage impact signal and a phase interval in which the phase of the power grid is located;

and correcting the specified phase by utilizing the determined phase adjustment step length according to the polarity of the voltage impact signal and the phase interval to obtain a specified trigger value for issuing a closing instruction next time.

Optionally, correcting the designated phase of the last determined closing instruction by using the determined phase adjustment step length according to the polarity of the voltage impact signal and the phase interval of the phase of the power grid to obtain a designated trigger value of the next closing instruction, including:

When the phase of the power grid is in a phase interval [ pi/2, 3 pi/2 ], and the polarity of the voltage impact signal is positive, determining a phase adjustment step length;

taking the sum of the designated phase of the last-determined issued closing instruction and the phase adjustment step length as the designated trigger value of the next-issued closing instruction;

when the phase of the power grid is in a phase interval [ pi/2, 3 pi/2 ] and the polarity of the voltage impact signal is negative, determining a phase adjustment step length;

and taking the difference value between the designated phase of the last determined issued closing instruction and the phase adjustment step length as a designated trigger value of the next issued closing instruction.

when the phase of the power grid is in the phase rangeOr->And the polarity of the voltage impact signal is positive, and the phase adjustment step length is determined;

taking the difference value between the designated phase of the last-determined issued closing instruction and the phase adjustment step length as the designated trigger value of the next-issued closing instruction;

When the phase of the power grid is in the phase rangeOr->When the polarity of the voltage impact signal is negative, determining a phase adjustment step length;

and taking the sum of the designated phase of the last determined issued closing instruction and the phase adjustment step length as the designated trigger value of the next issued closing instruction.

Optionally, the determining the phase adjustment step includes:

and acquiring a voltage impact value of the voltage impact signal, and determining a phase adjustment step length according to the voltage impact value, wherein the phase adjustment step length and the voltage impact value are positively correlated.

Optionally, if the specified trigger value is a specified voltage, correcting the specified trigger value of the last determined issued closing instruction based on the voltage impact signal to obtain the specified trigger value of the next issued closing instruction, including:

determining a polarity of the voltage surge signal;

if the polarity of the voltage impact signal is positive, determining a voltage adjustment step length;

taking the difference value between the designated voltage of the last-determined closing instruction and the voltage adjustment step length as the designated trigger value of the next closing instruction;

if the polarity of the voltage impact signal is negative, determining the voltage adjustment step length;

And taking the sum of the designated voltage which is determined before and sends the closing instruction and the voltage adjustment step length as the designated trigger value of the next closing instruction.

Optionally, the determining a voltage adjustment step includes:

and acquiring a voltage impact value of the voltage impact signal, and determining a voltage adjustment step length according to the voltage impact value, wherein the voltage adjustment step length and the voltage impact value are positively correlated.

Optionally, if the specified trigger value is a specified phase, correcting the specified trigger value of the last determined issued closing instruction based on the current impact signal to obtain the specified trigger value of the next issued closing instruction, including:

determining the generation time of the current impact signal;

calculating the actual closing time of the controllable switch according to the issuing time of the closing instruction and the generating time of the current impact signal;

Optionally, the method further comprises:

and in the process of controlling the controllable switch to be closed for multiple times, the frequency that the amplitude of the phase change value exceeds the preset amplitude reaches the preset frequency, and the controllable switch fault alarm is executed.

Optionally, if the specified trigger value is a specified phase, the method further includes:

and setting a designated trigger value for issuing a closing instruction for the first time according to the theoretical closing time of the controllable switch.

The second aspect of the embodiment of the invention discloses a control circuit of a controllable switch, which comprises: a controllable switch, a detection circuit and a controller;

the input end of the controllable switch is connected with a converter or a load, the output end of the controllable switch is connected with one input end of the power grid, the other input end of the power grid is connected with the converter or the load to obtain a loop formed by the converter or the load, the controllable switch and the power grid, and the intermediate equipment is the converter or the load between equipment to be connected with the power grid and the power grid;

the detection circuit is arranged at the input end and/or the output end of the controllable switch and is used for detecting impact signals generated at the input end and/or the output end of the controllable switch in real time in the process that the controllable switch is changed from an open state to a closed state;

The input end of the controller is connected with the output end of the detection circuit, the control end of the controller is connected with the movable end of the controllable switch, and the controller is used for executing the controllable switch control method disclosed in the first aspect of the embodiment of the invention.

Optionally, the detection circuit comprises a voltage detection circuit or a current sensor.

Optionally, the loop has 1 or more controllable switches in series, and the controllable switches include relays or circuit breakers.

Based on the control method and circuit of the controllable switch provided by the embodiment of the invention, the method is suitable for a power converter connected to a power grid, and the power converter at least comprises the controllable switch and a controller, and the method comprises the following steps: when the controllable switch is in an off state, acquiring power grid parameters of a power grid connected with an output end of the controllable switch in real time; when the power grid parameters reach the appointed trigger value of the last-time closing instruction, the controllable switch is controlled to be closed; the designated trigger value of the last issued closing instruction is determined according to an impact signal generated by the input end and/or the output end of the controllable switch in the closing process of the controllable switch. In the scheme, in the process of changing the controllable switch from the open state to the closed state every time, the appointed trigger value of the next issuing closing instruction is continuously corrected by utilizing the impact signal of any end of the controllable switch detected in real time, so that the controllable switch is ensured to be close to the real voltage zero crossing point every time when being closed, the impact is reduced, and the service life of the controllable switch is prolonged.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of a typical application scenario of a relay according to an embodiment of the present invention;

fig. 2 is a schematic diagram of an application scenario of a controllable switch control circuit according to an embodiment of the present invention;

fig. 3 is a schematic flow chart of a controllable switch control method according to an embodiment of the present invention;

FIG. 4 is a schematic flow chart of another method for controlling a controllable switch according to an embodiment of the present invention;

FIG. 5 is a timing chart for determining voltage impact applied to a controllable switch according to an embodiment of the present invention;

FIG. 6 is a schematic flow chart of another embodiment of a controllable switch control method;

FIG. 7 is a timing chart for determining the current surge applied to a controllable switch according to an embodiment of the present invention;

Fig. 8 is a schematic flow chart of a relay closing control method according to an embodiment of the present invention;

FIG. 9 is a timing diagram of adjusting a specified phase according to an embodiment of the present invention;

fig. 10 is a schematic flow chart of another relay closing control method according to an embodiment of the present invention;

FIG. 11 is a timing diagram for adjusting a specified voltage according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a controllable switch control circuit according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of another controllable switch control circuit according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

As known from the background art, the existing control method of the controllable switch is poor in applicability, and cannot enable the controllable switch to be close to a real voltage zero-crossing point as much as possible when the controllable switch is closed, so that impact cannot be reduced, and the service life of the controllable switch is influenced.

Therefore, in the scheme, in the process of changing the open state of the controllable switch from the closed state to the open state, the impact signals at the two ends of the controllable switch detected in real time are utilized to continuously correct the appointed trigger value of the next closing instruction, so that the situation that the controllable switch is close to the real voltage zero crossing point as much as possible is ensured, the impact is reduced, even no impact exists, and the service life of the controllable switch is further prolonged.

Fig. 2 is a schematic diagram of an application scenario of a control circuit of a controllable switch according to an embodiment of the present invention. The application scene is as follows:

the control circuit 22 of the controllable switch is arranged between the load 20 and the power grid 21, and when the load 20 is connected to the power grid 21, the control circuit 22 of the controllable switch ensures that the load 20 is safely disconnected from the power grid 21 in case of an abnormality. The control circuit 22 of the controllable switch at least comprises a controllable switch, a detection circuit connected to one or both ends of the controllable switch, and a controller connected to the detection circuit.

Preferably, the controllable switch control circuit 22 has 1 or more controllable switches connected in series.

Preferably, the controllable switch comprises a relay or a circuit breaker.

Preferably, the controller and controllable switch may be a controller and controllable switch in a power converter. The power converter may preferably be an inverter, in particular a grid-connected inverter.

Fig. 3 is a schematic flow chart of a control method of a controllable switch according to an embodiment of the present invention. The control method of the controllable switch is suitable for the control circuit 22 of the controllable switch shown in fig. 2 and the power converter connected to the power grid, and by utilizing the control method of the controllable switch disclosed by the embodiment of the invention, the control circuit 22 of the controllable switch or the controllable switch in the power converter can be ensured to be close to a real voltage zero-crossing point as much as possible when being closed each time, so that the impact is reduced, even no impact exists, and the service life of the controllable switch is further prolonged.

The control method of the controllable switch mainly comprises the following steps:

step S301: and when the controllable switch is in an off state, acquiring the power grid parameters of a power grid connected with the output end of the controllable switch in real time.

In step S301, the grid parameters include the phase of the grid and/or the voltage of the grid.

In step S301, the controllable switch includes a relay or a circuit breaker.

In the specific implementation process of step S301, the state of the controllable switch is detected in real time, and when the controllable switch is detected to be in the off state, the power grid parameters of the power grid connected with the output end of the controllable switch can be obtained in real time through detection.

In an embodiment of the present invention, if the power grid parameter obtained in real time is a voltage, specifically, when the controllable switch is in an off state, the power grid parameter of the power grid connected to the output end of the controllable switch is obtained in real time:

and when the controllable switch is in an off state, acquiring the voltage of the power grid connected with the output end of the controllable switch in real time.

In an embodiment of the present invention, if the power grid parameter obtained in real time is a phase, specifically, when the controllable switch is in an off state, the power grid parameter of the power grid connected to the output end of the controllable switch is obtained in real time as follows:

firstly, when a controllable switch is in an off state, acquiring the voltage of a power grid connected with the output end of the controllable switch in real time; and secondly, calculating the voltage of the power grid based on the phase-locked loop to obtain the phase of the power grid.

The phase of the grid is normally a linear interval of 0,2 pi.

Step S302: and when the power grid parameter reaches a designated trigger value which is determined in the last time and transmits a closing instruction, controlling the controllable switch to be closed.

In step S302, the specified trigger value refers to a value that triggers the controllable switch to close, and when the grid parameter reaches the specified trigger value, a closing instruction is issued. The specified trigger value is adjustable.

The initial value of the specified trigger value may be a value set by the user, or may be an empirical value, or may be an engineering calculation value.

Alternatively, the specified trigger value may be a specified phase or a specified voltage. If the specified trigger value is the specified phase, the power grid parameter obtained in step S301 is the phase of the power grid. If the specified trigger value is the specified voltage, the grid parameter obtained in step S301 is the voltage of the grid.

In the specific execution of step S302, the power grid parameter is compared with the designated trigger value designated by the previous determined issuing closure, and if the power grid parameter reaches the designated trigger value designated by the previous determined issuing closure, the controllable switch is controlled to be closed.

In an embodiment of the present invention, if the specified trigger value is a specified phase, the power grid parameter obtained in real time in step S301 includes a phase of the power grid, and in a process of specifically executing step S302, when the phase of the power grid reaches the specified phase of the current issuing closing instruction, the controllable switch is controlled to be closed.

In an embodiment of the present invention, if the specified trigger value is the specified voltage, the power grid parameter obtained in real time in step S301 includes the voltage of the power grid. In the process of specifically executing step S302, when the voltage of the power grid reaches the specified voltage of the current issuing of the closing instruction, the controllable switch is controlled to be closed.

In step S302, the designated trigger value of the last determined command for issuing a closing command is obtained by correcting the designated trigger value of the command for issuing a closing command based on the impact signal when the impact signal generated by the input end and/or the output end of the controllable switch is detected in real time in the process of controlling the controllable switch to be changed from the open state to the closed state.

In an embodiment of the present invention, after performing step S302, performing a specified trigger value calibration operation, where the specified trigger value calibration operation includes:

in the process of changing the controllable switch from the open state to the closed state, detecting whether an input end and/or an output end of the controllable switch generate an impact signal in real time, if any end generates the impact signal, correcting the designated trigger value of the last determined issuing closing instruction based on the impact signal, and taking the corrected designated trigger value as the designated trigger value of the next issuing closing instruction. If no impact signal is generated at any end, the controllable switch is indicated to be close to the real zero crossing point gradually, the appointed trigger value of the next issued closing instruction is not required to be corrected, and the current appointed trigger value, namely the appointed trigger value of the last determined issued closing instruction is still adopted as the appointed trigger value of the next issued closing instruction.

It should be noted that, at the moment of closing the controllable switch, if the voltages or currents at the input end and/or the output end of the controllable switch are different, and impact is generated, it is indicated that the closing of the controllable switch does not approach the real zero-crossing point, and the designated trigger value of the next closing instruction needs to be corrected, so as to ensure that the voltage approaches the real voltage zero-crossing point as much as possible when the controllable switch is closed each time, reduce the impact, and improve the service life of the controllable switch.

In one embodiment of the present invention, the specific process of performing the specified trigger value calibration operation includes:

in the process that the controllable switch is changed from an open state to a closed state, detecting whether the input end and/or the output end of the controllable switch generate a voltage impact signal or not in real time;

if the input end and/or the output end of the controllable switch generate a voltage impact signal, correcting the designated trigger value of the next designated trigger value of the controllable switch;

if the input end and the output end of the controllable switch do not generate voltage impact signals, the appointed trigger value of the last-determined issued closing instruction is continuously used as the appointed trigger value of the next issued closing instruction.

Detecting whether the input end and/or the output end of the controllable switch generate a current impact signal or not in real time in the process that the controllable switch is changed from an open state to a closed state;

if the input end and/or the output end of the controllable switch generate a current impact signal, correcting the appointed trigger value of the next issued closing instruction based on the current impact signal;

if the input end and the output end of the controllable switch do not generate current impact signals, the appointed trigger value of the last-determined issued closing instruction is continuously used as the appointed trigger value of the next issued closing instruction.

Based on the control method of the controllable switch provided by the embodiment of the invention, in the process of changing the open state of the controllable switch from the closed state to the open state, the impact signals at the two ends of the controllable switch detected in real time are utilized to continuously correct the appointed trigger value of the next closing instruction, so that the controllable switch is ensured to be close to the real voltage zero-crossing point as much as possible when being closed, the impact is reduced, and the service life of the controllable switch is prolonged.

Based on the above-mentioned control method of the controllable switch provided by the embodiment of the present invention, as shown in fig. 4, a flow chart of another control method of the controllable switch provided by the embodiment of the present invention is shown, in this embodiment, a trigger value is designated as a designated phase, and the control method of the controllable switch mainly includes the following steps:

Step S401: and when the controllable switch is in an off state, acquiring the phase of a power grid connected with the output end of the controllable switch in real time.

In the process of executing the step S401, firstly, when the controllable switch is in an off state, acquiring the voltage of a power grid connected with the output end of the controllable switch in real time; and then, calculating the voltage of the power grid based on the phase-locked loop to obtain the phase of the power grid.

Step S402: and when the phase of the power grid reaches the designated phase which is determined before and sends a closing instruction, controlling the controllable switch to be closed.

In step S402, when the specified trigger value is the specified phase, the first selection of the specified phase may be arbitrary. The designated phase for issuing the closing instruction for the first time can also be set according to the theoretical closing time of the controllable switch.

For example, given that the theoretical closing time of the controllable switch of a certain power segment is 5ms and the power grid period is 20ms, the specified phase θ0 of the first closing command may be

Step S403: in the process of changing the controllable switch from the open state to the closed state, detecting whether the input end and/or the output end of the controllable switch generate a voltage impact signal in real time, and executing S404 if the voltage impact signal is generated; if no voltage surge signal is generated, S409 is performed.

In step S403, the voltage at the input terminal and/or the output terminal of the controllable switch is detected, and the impact signal is a voltage impact signal.

It should be noted that, under the condition that the phase of the power grid is in the linear interval of [0,2 pi ], as shown in fig. 5, it is assumed that the sending time of the closing instruction corresponding to the designated phase is the time θ0 of the phase of the power grid, θ0 e [0,2 pi ] corresponds to the time sequence t0, in practical application, the time delay Ts of the controllable switch is actually closed, and because the time of triggering the controllable switch to be closed is not accurate enough and the uncertainty of the time delay Ts is likely to be not at the zero point of the power grid when the controllable switch is closed, a part of impact is likely to be generated. Therefore, in the embodiment of the present invention, when the input end and/or the output end of the controllable switch are detected to generate the voltage impact signal in the process of executing step S403, the time for triggering the controllable switch to close next time needs to be adjusted, and in the embodiment of the present invention, the designated phase needs to be adjusted.

Step S404: the moment of generation of the voltage surge signal is determined.

Based on the example shown in fig. 5, in the process of specifically executing step S404, after the action time delay Ts has elapsed, the generation timing of the voltage shock signal is determined to be t1.

Step S405: and determining the issuing time of the closing instruction according to the designated phase.

Based on the example shown in fig. 5, in the process of specifically executing step S405, the designated phase is θ0, and the issue time of the current closing instruction is t0.

It should be noted that, when the controllable switch is not controlled to be closed for the first time, the designated phase may be adjusted.

Step S406: and calculating the actual closing time of the controllable switch according to the issuing time of the closing instruction and the generating time of the voltage impact signal.

In step S406, the actual closing time of the controllable switch is the action delay Ts of the current controllable switch.

In the specific implementation process of step S406, the difference between the time t1 of generating the voltage impact signal and the time t0 of issuing the closing command is calculated, that is: ts= (t 1-t 0), the difference is the actual closing time of the controllable switch.

Based on the example shown in fig. 5, it is assumed that a voltage surge signal is detected by taking as an example the detection of the voltage at the input of the controllable switch.

Step S407: and calculating to obtain a phase change value according to the actual closing time of the controllable switch and the period of the power grid.

In the process of specifically executing step S407, based on formula (1), the actual closing time of the controllable switch and the grid period are used to perform conversion, so as to obtain the phase change value θs.

Wherein T is the power grid period, and Ts is the actual closing time of the controllable switch.

Step S408: and correcting the designated phase of the next issued closing instruction by using the phase change value to obtain the designated trigger value of the next issued closing instruction.

In the process of specifically executing step S408, the specified phase of the issued close command determined in the previous time is corrected by using the phase change value θs according to formula (2), so as to obtain the specified trigger value θ0' of the issued close specification in the next time.

θ0′＝k*π-θs (2)

Wherein k is greater than or equal to 1.

Step S409: and continuing to use the designated trigger value of the last determined issued closing instruction as the designated trigger value of the next issued closing instruction.

If no voltage surge signal is generated, step S409 is executed to indicate that the current controllable switch is closed to approach the real zero crossing point gradually, without correcting the designated trigger value of the next closing instruction, and when the next controllable switch is changed from the open state to the closed state, the timing of the closing instruction is still determined by adopting the designated trigger value of the last closing instruction.

In an embodiment of the present invention, in order to avoid that when the controllable switch is used for a long time, the action delay Ts of the controllable switch changes, so that the initial designated trigger value is not applicable any more, in the process of executing the controllable switch control method disclosed in the embodiment of the present invention, when the controllable switch is closed each time, the phase change value is repeatedly calculated once, and the designated trigger value (designated phase) is continuously corrected and updated by using the phase change value, so as to ensure that the controllable switch is closed exactly by zero crossing each time.

In practical application, through the first accurate calculation, when closing for the second time, the impact is not generated when the probability falls on the zero crossing point, so that the new action delay Ts may not be captured, and in this case, the specified trigger value (specified phase) is the ideal case, and the last specified trigger value is maintained.

In an embodiment of the present invention, in the process of executing the steps S401 to S408 for multiple times, that is, in the process of controlling the controllable switch to be turned on for multiple times, if the number of times that the amplitude of the phase change value exceeds the preset amplitude reaches the preset number of times, the controllable switch fault alarm is executed.

For example, the preset amplitude is pi/20, the preset times are 2 times, that is, in the process of controlling the controllable switch to be closed for many times, the amplitude of the phase change value exceeds pi/20 for 2 times, and then the controllable switch fault alarm is executed.

For example, the preset amplitude is pi/20, the preset times are 5 times, that is, in the process of controlling the controllable switch to be closed for many times, the amplitude of the phase change value exceeds pi/20 for 5 times, and then the controllable switch fault alarm is executed.

Based on the controllable switch control method disclosed by the embodiment of the invention, when the controllable switch is in an off state, the phase of a power grid connected with the output end of the controllable switch is obtained in real time; when the phase of the power grid reaches the designated phase of the last determined issuing of the closing instruction, the controllable switch is controlled to be closed; when the input end and/or the output end of the controllable switch generate voltage impact signals in real time in the process of changing the controllable switch from the open state to the closed state, correcting the designated phase of the last determined issuing closing instruction based on the voltage impact signals to obtain the designated phase of the next issuing closing instruction. In the scheme, in the process of changing the opening state of the controllable switch into the closing state every time, the appointed phase of the next closing instruction is continuously corrected by utilizing the voltage impact signal of any end of the controllable switch detected in real time, so that the controllable switch is ensured to be close to the real voltage zero crossing point every time when being closed, the impact is reduced, and the service life of the controllable switch is prolonged.

In the above embodiment, taking capturing a voltage impact signal of any end of a controllable switch as an example, the embodiment of the present invention may also capture a current impact signal of any end of a controllable switch, as shown in fig. 6, which is a schematic flow chart of another control method of a controllable switch according to the embodiment of the present invention, where the control method of a controllable switch mainly includes the following steps:

step S601: and when the controllable switch is in an off state, acquiring the phase of a power grid connected with the output end of the controllable switch in real time.

Step S602: and when the phase of the power grid reaches the designated phase which is determined before and sends a closing instruction, controlling the controllable switch to be closed.

Step S603: in the process of changing the controllable switch from the open state to the closed state, detecting whether the input end and/or the output end of the controllable switch generate a current surge signal in real time, and executing S604 if the current surge signal is generated; if the current surge signal is not generated, S609 is performed.

In step S603, the current at the input and/or the output of the controllable switch is detected, and the impact signal is a current impact signal.

Step S604: the moment of generation of the current surge signal is determined.

Step S605: and determining the issuing time of the closing instruction according to the designated phase.

Step S606: and calculating the actual closing time of the controllable switch according to the issuing time of the closing instruction and the generation time of the current impact signal.

Step S607: and calculating to obtain a phase change value according to the actual closing time of the controllable switch and the period of the power grid.

Step S608: and correcting the designated phase of the next issued closing instruction by using the phase change value to obtain the designated trigger value of the next issued closing instruction.

Step S609: and continuing to use the designated trigger value of the last determined issued closing instruction as the designated trigger value of the next issued closing instruction.

It should be noted that the execution principle and process of the steps S601 to S609 are similar to the execution principle and process of the steps S601 to S609 disclosed in fig. 4, and will not be repeated here.

In order to better understand the above, as shown in fig. 7, a control timing diagram for determining current impact on a controllable switch according to an embodiment of the present invention is provided.

The issuing instruction of the closing instruction corresponding to the designated phase is the time theta 0 of the phase of the power grid, the time theta 0 epsilon [0,2 pi ], and the corresponding time sequence t0, t2 is the generation time of the current impact signal. The actual closing time of the controllable switch is: ts= (t 2-t 0).

The designated trigger value θ0' of the next issuing closure designation can be obtained based on the formula (1) and the formula (2).

Based on the controllable switch control method provided by the embodiment of the invention, when the controllable switch is in the off state, the phase of the power grid connected with the output end of the controllable switch is obtained in real time; when the phase of the power grid reaches the designated phase of the last determined issuing of the closing instruction, the controllable switch is controlled to be closed; when the current impact signal generated at the input end and/or the output end of the controllable switch is detected in real time in the process that the controllable switch is changed from the open state to the closed state, the designated phase of the last determined closing instruction is corrected based on the current impact signal, and the designated phase of the next closing instruction is obtained. In the scheme, in the process of changing the opening state of the controllable switch into the closing state every time, the appointed phase of the next closing instruction is continuously corrected by utilizing the current impact signal of any end of the controllable switch detected in real time, so that the controllable switch is ensured to be close to the real voltage zero crossing point every time when being closed, the impact is reduced, and the service life of the controllable switch is prolonged.

It should be noted that, based on the controllable switch control method disclosed in the embodiment of the present invention, no matter what type or signal the controllable switch is, whether or not the controllable switch has a feedback node, the controllable switch control method can be automatically adapted, because the action delay Ts is detected online, it can be ensured that the controllable switch is at a real zero crossing point as much as possible when the closing action occurs, and the service life is prolonged.

The controllable switch control method provided by the embodiment of the invention can directly obtain the action delay and then adjust the designated phase based on the value. The controllable switch control method disclosed in the embodiment of the invention is not limited to adopting action delay to adjust the designated phase. As shown in fig. 8, if the specified trigger value is the specified phase, a flow chart of another controllable switch control method according to an embodiment of the present invention is provided, where the controllable switch control method mainly includes the following steps:

step S801: and when the controllable switch is in an off state, acquiring the phase of a power grid connected with the output end of the controllable switch in real time.

Step S802: and when the phase of the power grid reaches the designated phase which is determined before and sends a closing instruction, controlling the controllable switch to be closed.

Step S803: in the process of changing the controllable switch from the open state to the closed state, detecting whether the input end and/or the output end of the controllable switch generate a voltage impact signal in real time, and executing S804 if the voltage impact signal is generated; if the voltage surge signal is not generated, S806 is performed.

The specific implementation process and principle of the above steps S801 to S803 are the same as those of the steps S401 to S403 shown in fig. 4, and will not be repeated here.

Step S804: the polarity of the voltage surge signal and the phase interval in which the phase of the power grid is located are determined.

In step S804, the polarity of the voltage surge signal is positive or negative, and by determining the positive polarity or negative polarity of the voltage surge signal, it can be determined at which end of the controllable switch the voltage surge occurs when the controllable switch is closed.

In step S804, the phase interval in which the phase of the power grid is located is determined by the power grid voltage change when the voltage surge is generated. Assuming that the input of the controllable switch generates a voltage surge signal, if the voltage change of the network grows negatively, i.e. from large to small, the networkThe phase is in the phase interval of [ pi/2, 3 pi/2]. If the voltage change of the power grid is positive, namely from small to large, the phase interval where the phase of the power grid is located is

Step S805: and correcting the designated phase of the last determined issued closing instruction by utilizing the determined phase adjustment step length according to the polarity and the phase interval of the voltage impact signal to obtain the designated trigger value of the next issued closing instruction.

Step S806: and continuing to use the designated trigger value of the last determined issued closing instruction as the designated trigger value of the next issued closing instruction.

In step S805, the phase adjustment step size determination process is: and acquiring a voltage impact value of the voltage impact signal, and determining a phase adjustment step length according to the voltage impact value.

For example, when the voltage surge value is large, the phase adjustment step size will be larger, and when the voltage surge value is small, the phase adjustment step size will be smaller, and the actual zero crossing point will be gradually approached.

Specifically, the phase adjustment step size is positively correlated with the voltage surge value. Specifically as shown in formula (3).

Δθ＝kΔu (3)

Wherein, delta theta is the phase adjustment step length, delta u is the voltage impact value, and k is more than or equal to 1.

In one embodiment of the present invention, the process of step S805 is specifically performed:

step S8051: when the phase of the power grid is in the phase interval [ pi/2, 3 pi/2 ], judging whether the polarity of the voltage impact signal is positive, if so, executing step S8052; if negative, step S8054 is performed.

In the process of executing step S8051 specifically, if the phase of the power grid is determined to be in the phase interval θ0∈ [ pi/2, 3pi/2 ], if the polarity of the voltage surge signal is positive, it is indicated that the actual closing moment of the controllable switch occurs on the left side of the theoretical position pi, the designated phase θ0 of the last determined issued closing command should be shifted to the right, i.e. a phase adjustment step Δθ is added, and the generated offset is compensated, i.e. step S8052 is executed.

If the polarity of the voltage surge signal is negative, which indicates that the actual closing time of the controllable switch occurs on the right side of the theoretical position pi, the designated phase θ0 of the previously determined issued closing command should be shifted to the left, i.e. the phase adjustment step Δθ is reduced, and the resulting shift is compensated, step S8054 is performed.

Step S8052: a phase adjustment step size is determined.

In the process of specifically executing step S8052, a phase adjustment step Δθ is generated according to formula (3).

Step S8053: and taking the sum value of the designated phase of the last-determined issued closing instruction and the phase adjustment step length as the designated trigger value of the next-issued closing instruction.

In the specific execution of step S8053, a sum value (θ0+Δθ) of the designated phase θ0 of the next issued close instruction and the phase adjustment step Δθ determined in the previous time is obtained, and the sum value (θ0+Δθ) is used as the designated trigger value of the next issued close instruction.

Step S8054: a phase adjustment step size is determined.

In the process of specifically executing step S7054, one phase adjustment step Δθ is generated according to formula (3).

Step S8055: and taking the difference value between the designated phase of the last determined issued closing instruction and the phase adjustment step length as the designated trigger value of the next issued closing instruction.

In the specific execution of step S8055, a difference value (θ0- Δθ) between the designated phase θ0 of the next issued close instruction and the phase adjustment step Δθ, which is determined in the previous time, is obtained, and the difference value (θ0- Δθ) is used as the designated trigger value of the next issued close instruction.

Taking fig. 9 as an example, assume that the sending time of the closing command corresponding to the designated phase is the time θ0 of the phase of the power grid, θ0 e [0, 2pi ], at this time, the input end of the controllable switch generates a voltage impact signal, the power grid voltage changes to be negative, at this time, the phase interval where the phase of the power grid is located is [ pi/2, 3pi/2 ], and the following adjustment logic is obtained according to the polarity judgment of the voltage impact signal:

when theta 0 is [ pi/2, 3 pi/2 ],

(1) The polarity of the voltage impact signal is positive, and the designated trigger value (action moment) of the next closing instruction is: θ0+Δθ;

(2) The polarity of the voltage impact signal is negative, and the designated trigger value (action moment) of the next closing instruction is as follows: θ0- Δθ.

step S8056: when the phase of the power grid is in the phase rangeJudging whether the polarity of the voltage impact signal is positive, if so, executing step S8057; if negative, step S8059 is performed.

In the process of specifically executing step S8056, when determining that the phase of the power grid is in the phase zoneIf the polarity of the voltage surge signal is positive, it indicates that the actual closing time of the controllable switch occurs on the right side of the theoretical position pi, the designated phase θ0 of the previously determined issued closing command should be shifted to the left, i.e. reduced by one phase adjustment step Δθ, to compensate for the resulting offset, i.e. step S8057 is performed.

If the polarity of the voltage surge signal is negative, which indicates that the actual closing time of the controllable switch occurs at the left side of the theoretical position pi, the designated phase θ0 of the previously determined issued closing command should be shifted to the right, i.e. a phase adjustment step Δθ is added to compensate the generated offset, and step S8059 is performed.

Step S8057: a phase adjustment step size is determined.

In the process of specifically executing step S8057, a phase adjustment step Δθ is generated according to formula (3).

Step S8058: and taking the difference value between the designated phase of the last determined issued closing instruction and the phase adjustment step length as the designated trigger value of the next issued closing instruction.

In the specific execution of step S8058, a difference value (θ0- Δθ) between the designated phase θ0 of the next issued close instruction and the phase adjustment step Δθ, which is determined in the previous time, is obtained, and the difference value (θ0- Δθ) is used as the designated trigger value of the next issued close instruction.

Step S8059: a phase adjustment step size is determined.

In the process of specifically executing step S8059, one phase adjustment step Δθ is generated according to formula (3).

Step S8050: and taking the sum value of the designated phase of the last-determined issued closing instruction and the phase adjustment step length as the designated trigger value of the next-issued closing instruction.

In the specific execution of step S8050, a sum value (θ0+Δθ) of the designated phase θ0 of the next issued close instruction and the phase adjustment step Δθ determined in the previous time is obtained, and the sum value (θ0+Δθ) is used as a designated trigger value of the next issued close instruction.

For example, assume that the time of issuing the closing command corresponding to the specified phase is time θ0 of the phase of the power grid, θ0 ε [0,2π]At the moment, the input end of the controllable switch generates a voltage impact signal, the voltage of the power grid is changed to be positive growth, and the phase interval where the phase of the power grid is located isAccording to the polarity judgment of the voltage impact signal, the following adjustment logic is obtained:

when (when)In the time-course of which the first and second contact surfaces,

(1) The polarity of the voltage impact signal is positive, and the designated trigger value (action moment) of the next closing instruction is: θ0- Δθ;

(2) The polarity of the voltage impact signal is negative, and the designated trigger value (action moment) of the next closing instruction is as follows: θ0+Δθ.

Based on the controllable switch control method disclosed by the embodiment of the invention, the controllable switch can be controlled in the mode no matter whether the input end or the output end of the controllable switch generates impact signals.

Based on the controllable switch control method disclosed by the embodiment of the invention, the polarity of the voltage impact signal is detected every time the controllable switch is closed, and the moment of issuing the closing instruction next time is gradually and finely adjusted according to the phase interval where the phase of the power grid is positioned and the adjusting logic of the polarity of the voltage impact signal to the appointed trigger value (appointed trigger phase), so that the voltage impact is smaller and smaller, the purpose of no impact is finally realized, the controllable switch is close to the real voltage zero crossing point as much as possible, the impact is reduced, and the service life of the relay is prolonged.

It should be noted that the above-mentioned controllable switch control method is to adjust the specified trigger value by means of the phase of the power grid and the polarity of the voltage surge signal. If the specified trigger value is the specified voltage, the voltage of the power grid can also be directly collected for judgment, and specifically, as shown in fig. 10, a flow diagram of another controllable switch control method disclosed in the embodiment of the invention is provided, and the controllable switch control method mainly includes the following steps:

Step S1001: and when the controllable switch is in an off state, acquiring the voltage of the power grid connected with the output end of the controllable switch in real time.

Step S1002: and when the voltage of the power grid reaches the designated voltage which is determined before and sends a closing instruction, controlling the controllable switch to be closed.

The specific implementation process of the above step S1001 and step S1002 is similar to the principle of step S301 and step S302 shown in fig. 3, and will not be repeated here.

Step S1003: in the process of changing the controllable switch from the open state to the closed state, detecting whether the input end and/or the output end of the controllable switch generate a voltage impact signal in real time, and executing S1004 if the voltage impact signal is generated; if the voltage surge signal is not generated, S1009 is performed.

The specific implementation process of the above step S1003 is the same as the principle of step S403 shown in fig. 4, and will not be described here again.

Step S1004: determining the polarity of the voltage surge signal, if the polarity of the voltage surge signal is positive, executing step S1005; if the polarity of the voltage surge signal is negative, step S1007 is performed.

In step S1004, the polarity of the voltage surge signal is positive or negative, and by determining the positive polarity or negative polarity of the voltage surge signal, it is possible to determine at which end of the controllable switch the voltage surge occurs when the controllable switch is closed.

In the process of specifically executing step S1004, if the polarity of the voltage surge signal is positive, the moment of actually closing the controllable switch is indicated to be at the left side of the theoretical position 0V, the designated voltage u0 that issued the closing command determined previously should be shifted to the right, i.e. reduced by one voltage adjustment step Δu', and the offset generated is compensated, i.e. steps S1005 to S1006 are executed.

If the polarity of the voltage surge signal is negative, the moment of the actual closing of the controllable switch occurs on the right side of the theoretical position 0V, the designated voltage u0 that issued the closing command determined previously should be shifted to the left, i.e. increased by a voltage adjustment step Δu', and the resulting offset is compensated, i.e. steps S1007 to S1008 are performed.

Step S1005: a voltage adjustment step size is determined.

The specific process of executing step S1005 is: and acquiring a voltage impact value of the voltage impact signal, and determining a voltage adjustment step length according to the voltage impact value.

For example, when the voltage surge value is large, the voltage adjustment step size will be larger, and when the voltage surge value is small, the voltage adjustment step size will be smaller, and the actual zero crossing point will be gradually approached.

Specifically, the voltage adjustment step size is positively correlated with the voltage surge value. Specifically as shown in formula (4).

Δu′＝kΔu (4)

Wherein Deltau' is the phase adjustment step length, deltau is the voltage impact value, and k is more than or equal to 1.

Step S1006: and taking the difference value between the designated voltage of the last-determined closing instruction and the voltage adjustment step length as the designated trigger value of the next closing instruction.

In the specific execution of step S1006, a difference (u 0- Δu ') between the designated voltage u0 of the next issued close instruction and the voltage adjustment step Δu ' determined in the previous time is obtained, and the difference (u 0- Δu ') is used as the designated trigger value of the next issued close instruction.

Step S1007: a voltage adjustment step size is determined.

In the process of specifically executing step S1007, a voltage adjustment step Δu' is generated according to equation (4).

Step S1008: and taking the sum of the designated voltage of the last-determined closing instruction and the voltage adjustment step length as the designated trigger value of the next closing instruction.

In the specific execution of step S1006, a sum (u0+Δu ') of the designated voltage u0 of the next issued closing instruction and the voltage adjustment step Δu ' determined in the previous time is obtained, and the sum (u0+Δu ') is used as the designated trigger value of the next issued closing instruction.

Step S1009: and continuing to use the designated trigger value of the last determined issued closing instruction as the designated trigger value of the next issued closing instruction.

Taking fig. 11 as an example, assume that the time of issuing the closing command corresponding to the specified voltage is u0, at this time, the input end of the controllable switch generates a voltage surge signal, and the following adjustment logic is obtained according to the polarity judgment of the voltage surge signal:

(1) The polarity of the voltage impact signal is positive, and the designated trigger value (action moment) of the next closing instruction is: u0- Δu';

(2) The polarity of the voltage impact signal is negative, and the designated trigger value (action moment) of the next closing instruction is as follows: u0+Δu'.

Based on the controllable switch control method disclosed by the embodiment of the invention, the polarity of the voltage impact signal is detected when the controllable switch is closed every time, the moment of issuing the closing instruction next time is gradually and finely adjusted according to the appointed voltage and the adjusting logic of the polarity of the voltage impact signal to the appointed trigger value (appointed voltage), so that the voltage impact is smaller and smaller, the purpose of no impact is finally realized, the controllable switch is close to the real voltage zero crossing point as much as possible when the controllable switch is closed, the impact is reduced, and the service life of the relay is prolonged.

Based on the control method of the controllable switch disclosed in the embodiment of the present invention, the embodiment of the present invention also correspondingly discloses a control circuit of the controllable switch, as shown in fig. 12, where the control circuit of the controllable switch includes: a controllable switch 120, a detection circuit (not shown in the figure) and a controller 121.

The input end of the controllable switch 120 is connected with a converter or a load (shown by words in the figure), the output end of the controllable switch 120 is connected with one input end of the power grid 21, the other input end of the power grid 21 is connected with the converter or the load, and a loop is formed by the converter or the load, the controllable switch 120 and the power grid 21.

In one embodiment of the invention, there are 1 or more controllable switches 120 in series in the loop.

In one embodiment of the present invention, the controllable switch 120 comprises a relay or a circuit breaker.

In an embodiment of the present invention, the controllable switch 120 and the controller 121 are controllable switches and controllers in a power converter connected to a power grid, preferably, the power converter is an inverter, particularly a grid-connected inverter.

The detection circuit is disposed at an input end and/or an output end of the controllable switch 120, and is configured to detect an impact signal generated at the input end and/or the output end of the controllable switch 120 in real time during a process of changing the controllable switch 120 from an open state to a closed state.

The input end of the controller 121 is connected to the output end of the detection circuit, and the control end of the controller 121 is connected to the movable end of the controllable switch 120, where the controller is configured to execute any of the controllable switch control methods disclosed in the embodiments of the present invention.

In one embodiment of the present invention, the detection circuit includes a voltage detection circuit or a current sensor.

The voltage detection circuit is configured to detect a voltage surge signal at an input and/or an output of the controllable switch 120.

As shown in fig. 13, in another embodiment of the present invention, a voltage detection circuit 122 is disposed at an output end of the controllable switch 120 for detecting a voltage surge signal at the output end of the controllable switch 120.

The current sensor is disposed at an input end and/or an output end of the controllable switch 120, and is configured to detect a current impact signal at the input end and/or the output end of the controllable switch 120.

Based on the control circuit of the controllable switch provided by the embodiment of the invention, in the process of changing the controllable switch from the open state to the closed state every time, the appointed trigger value of the next closing instruction is continuously corrected by utilizing the impact signals at the two ends of the controllable switch detected in real time, so that the controllable switch is ensured to be close to the real voltage zero crossing point every time when being closed, the impact is reduced, and the service life of the controllable switch is prolonged.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. 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 this application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of controlling a controllable switch, characterized by a power converter adapted for access to an electrical grid, the power converter comprising at least the controllable switch and a controller, the method comprising:

2. The method of claim 1, wherein the grid parameter comprises a phase, and wherein the specified trigger value is a specified phase;

correspondingly, when the power grid parameter reaches a designated trigger value which is determined before and sends a closing instruction, the switch is controlled to be closed, and the method comprises the following steps:

3. The method of claim 1, wherein the grid parameter comprises a voltage, and wherein the specified trigger value is a specified voltage;

4. A method according to any one of claims 1 to 3, further comprising, in controlling the closing of the controllable switch:

5. The method of claim 4, wherein if the specified trigger value is a specified phase, correcting the specified trigger value of the previously determined issued close command based on the voltage surge signal to obtain the specified trigger value of the next issued close command, comprising:

determining the generation time of the voltage impact signal;

6. The method of claim 4, wherein if the specified trigger value is a specified phase, correcting the specified trigger value of the previously determined issued close command based on the voltage surge signal to obtain the specified trigger value of the next issued close command, comprising:

and correcting the designated phase of the last determined closing instruction by utilizing the determined phase adjustment step length according to the polarity of the voltage impact signal and the phase interval to obtain the designated trigger value of the next closing instruction.

7. The method of claim 6, wherein correcting the specified phase of the previously determined issued close command with the determined phase adjustment step size based on the polarity of the voltage surge signal and the phase interval of the phase of the power grid to obtain the specified trigger value of the next issued close command comprises:

8. The method of claim 6, wherein correcting the specified phase of the previously determined issued close command with the determined phase adjustment step size based on the polarity of the voltage surge signal and the phase interval of the phase of the power grid to obtain the specified trigger value of the next issued close command comprises:

9. The method according to any one of claims 6 to 8, wherein the determining a phase adjustment step size comprises:

10. The method of claim 4, wherein if the specified trigger value is a specified voltage, correcting the specified trigger value of the previous issued close command based on the voltage surge signal to obtain the specified trigger value of the next issued close command, comprising:

determining a polarity of the voltage surge signal;

and taking the sum of the designated voltage of the last-determined closing instruction and the voltage adjustment step length as the designated trigger value of the next closing instruction.

11. The method of claim 10, wherein the determining a voltage adjustment step size comprises:

12. The method of claim 4, wherein if the specified trigger value is a specified phase, correcting the specified trigger value of the previous issued close command based on the current surge signal to obtain the specified trigger value of the next issued close command, comprising:

Determining the generation time of the current impact signal;

13. The method according to claim 5 or 12, further comprising:

and in the process of controlling the switch to be closed for multiple times, the frequency that the amplitude of the phase change value exceeds the preset amplitude reaches the preset frequency, and the switch fault warning is executed.

14. The method of any one of claims 1 to 3, 5 or 12, further comprising, if the specified trigger value is a specified phase:

and setting a designated trigger value for issuing a closing instruction for the first time according to the theoretical closing time of the switch.

15. A control circuit for a controllable switch, comprising: a controllable switch, a detection circuit and a controller;

The input end of the controllable switch is connected with a converter or a load, the output end of the controllable switch is connected with one input end of the power grid, and the other input end of the power grid is connected with the converter or the load to obtain a loop formed by the converter or the load, the controllable switch and the power grid;

the input end of the controller is connected with the output end of the detection circuit, the control end of the controller is connected with the movable end of the switch, and the controller is used for executing the switch control method of any one of claims 1 to 14.

16. The switch control circuit of claim 15, wherein the detection circuit comprises a voltage detection circuit or a current sensor.

17. The switch control circuit of claim 15, wherein there are 1 or more controllable switches in series in the loop, the controllable switches comprising relays or circuit breakers.