CN117741425A - Switch detection device of power system and power system - Google Patents
Switch detection device of power system and power system Download PDFInfo
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Abstract
The application relates to a power system and power system's switch detection device, wherein, switch detection device includes: the current sampling circuit is connected with the bus and used for collecting current signals of the power network side; the driving circuit is connected with the change-over switch and used for providing a driving signal to the change-over switch so as to control the on-off state of the change-over switch; the control circuit is respectively connected with the current sampling circuit and the driving circuit and is used for respectively acquiring a first current signal before the driving signal is provided to the change-over switch and a second current signal after the driving signal is provided to the change-over switch, and determining the on-off state of the change-over switch according to the driving signal, the first current signal and the second current signal, so that the state of the change-over switch can be effectively monitored, and the safety and reliability of a power system can be improved.
Description
Technical Field
The application relates to the technical field of optical storage systems, in particular to a switch detection device of a power system and the power system.
Background
At present, in a power system (such as new energy power generation and an energy storage system), two working conditions of grid connection and grid disconnection generally occur, in the related technology, devices such as a contactor and a relay are generally adopted to conduct grid connection and grid disconnection switching, but as the requirement of a load on the allowable power failure time is further reduced, the conventional mechanical switch action time does not meet the requirement, and at present, a power electronic fast switch is increasingly adopted to conduct grid connection and grid disconnection switching.
However, in the process of switching off the grid, only the factors such as voltage, phase and frequency of the power grid and the load side are generally concerned, grid connection can be achieved if the requirements are met, the power grid is powered down, namely the off-grid working condition is switched off, and detection of the state of the switch is often ignored.
Disclosure of Invention
In view of the above, it is necessary to provide a power system, which can effectively monitor the state of a change-over switch and can improve the safety and reliability of the power system.
The application provides a power system's switch detection device, switch detection device includes: the current sampling circuit is connected with the bus and used for collecting current signals of the power network side;
the driving circuit is connected with the change-over switch and used for providing a driving signal to the change-over switch so as to control the on-off state of the change-over switch;
the control circuit is respectively connected with the current sampling circuit and the driving circuit and is used for respectively acquiring a first current signal before the driving signal is provided to the change-over switch and a second current signal after the driving signal is provided to the change-over switch, and determining the on-off state of the change-over switch according to the driving signal, the first current signal and the second current signal.
In one embodiment, the control circuit is further configured to determine that the change-over switch is in a conductive state when the driving signal is normal and the amounts of change of the first current signal and the second current signal exceed a threshold range;
the control circuit is further configured to determine that the change-over switch is in an off state when the amounts of change of the first current signal and the second current signal are within the threshold range.
In one embodiment, the switch detection device further includes:
the two output ends of the excitation circuit are respectively and correspondingly connected with buses on two sides of the change-over switch;
the detection circuit is connected with the excitation circuit and is used for detecting the current value of the primary side of the excitation circuit; wherein,
the control circuit is also respectively connected with the excitation circuit and the detection circuit and is used for controlling the excitation circuit to provide an excitation signal to the bus and determining the on-off state of the change-over switch according to the acquired current value of the primary side of the excitation circuit under the condition that the driving signal is normal and the variation of the first current signal and the second current signal exceeds a threshold range.
In one embodiment, the control circuit is further configured to determine that the switch is in an off state when the driving signal is normal, the variation amounts of the first current signal and the second current signal exceed a threshold range, and the current value on the primary side of the excitation circuit does not meet a preset condition; and the control circuit is further used for determining that the change-over switch is in a conducting state under the condition that the driving signal is normal, the variation of the first current signal and the second current signal exceeds a threshold range and the current value of the primary side of the excitation circuit meets a preset condition.
In one embodiment, the excitation circuit includes:
an excitation power supply for providing the excitation signal;
and the excitation switch unit is respectively connected with the excitation power supply, buses at two sides of the change-over switch and the control circuit and is used for conducting under the action of the control circuit so as to transmit the excitation signal to the buses.
In one embodiment, the control circuit is further configured to determine a fault type of the power system according to the driving signal, the first current signal, the second current signal, and the on-off state of the excitation switch unit, where the fault type includes a change-over switch fault, the current sampling circuit fault, the detection circuit fault, and the driving circuit fault.
In one embodiment, the control circuit is further configured to:
determining that the change-over switch has a fault when the driving signal is normal, the variation of the first current signal and the second current signal is within the threshold range, and the excitation switch unit is in an off state;
determining that the current sampling circuit is faulty when the driving signal is normal, the variation amounts of the first current signal and the second current signal are within the threshold range, and the excitation switch unit is in a conducting state;
determining that the detection circuit is faulty when the driving signal is normal, the variation of the first current signal and the second current signal exceeds a threshold range, and the excitation switch unit is in an off state;
and determining that the driving circuit is faulty when the driving signal is abnormal, the variation of the first current signal and the second current signal exceeds a threshold range, and the excitation switch unit is in an off state.
The present application also provides a power system comprising: energy storage system, power network, change-over switch and switch detection device as aforesaid.
In one embodiment, the energy storage system comprises: the power supply device comprises an inverter, an energy storage converter and a switch circuit, wherein a first end of the switch circuit is connected with a bus, and a plurality of second ends of the switch circuit are correspondingly connected with the inverter, the energy storage converter and a load respectively; wherein,
when the power system is in load and off-grid switching, the switch detection device is used for determining the on-off state of the switching switch according to the driving signal, the first current signal and the second current signal.
In one embodiment, when the switch detection device includes an excitation circuit and a detection circuit, and the driving signal is normal and the variation amounts of the first current signal and the second current signal exceed a threshold range when the power system is in load and off-grid switching, the switch detection device is further configured to control the excitation circuit to provide an excitation signal to the bus, and determine the on-off state of the switch according to the obtained current value of the primary side of the excitation circuit.
In one embodiment, the switch detection device is further configured to control the excitation circuit to provide an excitation signal to the bus and determine the on-off state of the switch according to the obtained current value of the primary side of the excitation circuit when the power system is not loaded and switched off from the grid.
In one embodiment, the switch detection device is further configured to output a fault instruction to the energy storage system to stop the energy storage system when it is determined that the power system fails.
The switch detection device and the power system provided by the embodiment comprise a current sampling circuit, a driving circuit and a control circuit, wherein the current sampling circuit is connected with a bus, the driving circuit is connected with a switch, the control circuit is respectively connected with the current sampling circuit and the driving circuit, the control circuit can acquire a driving signal provided by the driving circuit to a thyristor, acquire a first current signal before the switch receives the driving signal and a second current signal after the switch receives the driving signal from the current sampling circuit, and determine the on-off state of the thyristor based on the acquired driving signal, the first current signal and the second current signal, so that the on-off state of the switch can be rapidly and accurately determined. Further, in the process of determining the on-off state of the thyristor, the control circuit comprehensively considers a plurality of factors of current changes of the driving signal and the power grid side current signal before and after the driving signal is received by the change-over switch, so that the judgment accuracy of the on-off state of the change-over switch can be improved. The on-off or off state of the change-over switch plays a key role in the process of off-grid switching or in-grid switching of the power system. In the embodiment of the application, the switch detection device can rapidly and accurately determine the on-off state of the change-over switch, and then the safety and reliability of the power system can be improved. Furthermore, the current sampling circuit of the switch detection device can be reused as the current sampling circuit in the power system, so that the cost can be reduced.
Drawings
In order to more clearly illustrate the technical solutions of embodiments or conventional techniques of the present application, the drawings required for the descriptions of the embodiments or conventional techniques will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person of ordinary skill in the art.
FIG. 1 is one of block diagrams of a switch detection device of an electric power system according to an embodiment;
FIG. 2 is a second block diagram of a switch detection device of an electric power system according to an embodiment;
FIG. 3 is a third block diagram of a switch detection device of an electrical power system according to an embodiment;
FIG. 4 is a block diagram of a power system of an embodiment;
FIG. 5 is a block diagram of another embodiment of a power system;
FIG. 6 is a flow chart of the operation of the power system of an embodiment;
fig. 7 is a flowchart of the operation of the power system of another embodiment.
Reference numerals illustrate:
10-energy storage system, 110-inverter, 120-energy storage converter, 130-switching circuit, 140-load, QF 1-first breaker, QF 2-second breaker, QF 3-third breaker, 20-power network, 30-change-over switch, 40-switch detection device, 410-current sampling circuit, 420-driving circuit, 430-control circuit, 440-excitation circuit, 441-excitation power supply, 443-excitation switch unit, 450-detection circuit.
Detailed Description
In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Examples of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that the terms "first," "second," and the like, as used herein, may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. It is to be understood that in the following embodiments, "connected" is understood to mean "electrically connected", "communicatively connected", etc., if the connected circuits, modules, units, etc., have electrical or data transfer between them.
It is understood that "at least one" means one or more and "a plurality" means two or more. "at least part of an element" means part or all of the element. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," and/or the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Also, the term "and/or" as used in this specification includes any and all combinations of the associated listed items.
As shown in fig. 1, in the embodiment of the application, a switch detection device of a power system is provided, and it can be understood that the switch detection device provided in the embodiment of the application can be applied to the power system. The power system comprises an energy storage system 10, a power network 20 and a change-over switch 30, wherein the energy storage system 10 is connected with the power network 20 through a bus, and the change-over switch 30 is connected in series with the bus. The energy storage system 10 may include at least one of an inverter and an energy storage converter. The number of the energy storage converters can be one or a plurality of the energy storage converters. Accordingly, the number of inverters may be one or a plurality of inverters. The input ends of the energy storage converter and the inverter can be connected with a battery and a photovoltaic, and it is understood that the input ends of the energy storage converter and the inverter can be only connected with the battery and not connected with the photovoltaic, and the energy storage converter and the inverter are not particularly limited. The energy storage converter can charge the battery and discharge the battery. The power network 20 may include an electrical grid, a diesel network, and the like. In the present embodiment, the power network 20 is exemplified as an electric grid. The power system also comprises a contactor KM connected in series with the bus. Optionally, the power system further comprises a circuit breaker QF (not shown) or the like connected in series with the bus bar.
The switch 30 may be understood as a fast switch, and the switch 30 may be an electronic switching tube such as a thyristor suitable for an ac system, for example. In the related technology, in the process of grid-connected and off-grid switching, only factors such as voltage, phase and frequency of a power grid and a load side are generally concerned, when the energy storage systems at two sides of a thyristor are synchronous with the voltage, phase and frequency of a power grid, the off-grid switching condition is met, and correspondingly, when the power grid is powered down, the grid-connected switching off condition is met, but the switching of the on-off state of the thyristor is often ignored.
Based on this, please continue to refer to fig. 1, the embodiment of the present application provides a switch detection device, which can effectively monitor the state of the change-over switch 30 in the power system, so as to facilitate remote maintenance and troubleshooting and make corresponding countermeasures, improve maintenance efficiency, reduce maintenance cost, and improve reliability of the power system.
In the embodiment of the present application, the switch detection device 40 includes: a current sampling circuit 410, a driving circuit 420, and a control circuit 430. The current sampling circuit 410 is connected to the bus bar, the driving circuit 420 is connected to the switch 30, and the control circuit 430 is connected to the current sampling circuit 410 and the driving circuit 420, respectively.
The current sampling circuit 410 is used to collect current signals on the power network 20 side. The node where the current sampling circuit 410 is connected to the bus is located on the bus between the power network 20 and the switch 30, so that the current sampling circuit 410 can collect the current signal on the bus on the power network 20 side. The current sampling circuit 410 may be a non-isolated current sampling circuit, such as a current divider circuit. The current sampling circuit 410 may also be an isolated current sampling circuit, and may include, for example, a hall current sensor. In the embodiment of the present application, the specific form of the current sampling circuit 410 is not specifically limited, nor is it limited to the above-described example.
The driving circuit 420 is used for providing a driving signal to the switch 30 to control the on-off state of the switch 30. The switch 30 is a thyristor, and a driving signal provided by the driving circuit 420 may be connected to a control terminal of the thyristor to control the on-off state of the thyristor. Wherein the drive signal may comprise a drive current, such as a pulsed current or the like. Illustratively, the drive circuit 420 may include a gate drive circuit 420. Specifically, the gate driving circuit 420 may include a gate on circuit and a gate off circuit, the gate on circuit providing a positive gate pulse current when the thyristor is on. The gate turn-off circuit provides a negative gate pulse current for the thyristor when turned off.
The control circuit 430 is configured to obtain a first current signal before the driving signal is provided to the switch 30 and a second current signal after the driving signal is provided to the switch 30, and determine an on-off state of the switch 30 according to the driving signal, the first current signal, and the second current signal. The current sampling circuit 410 may collect the current signal on the grid side in real time, for example, the current sampling circuit 410 may collect the first current signal on the grid side before the driving signal is provided to the switch 30, and the current sampling circuit 410 may collect the second current signal on the grid side after the driving signal is provided to the switch 30. The timing of providing the driving signal may be determined by the driving circuit 420 or may be determined by the control circuit 430, for example, the control circuit 430 may control the driving circuit 420 to provide the driving signal to the thyristor.
The control circuit 430 may obtain a drive signal provided to the thyristor by the drive circuit 420, and obtain a first current signal and a second current signal from the current sampling circuit 410, and determine whether the thyristor is in an on or off state based on the obtained drive signal, the first current signal, and the second current signal. The control circuit 430 can determine, based on the first current signal and the second current signal, a current change of the grid-side current signal before and after the change-over switch 30 receives the driving signal, and further can determine, based on the driving signal and the current change, an on-off state of the change-over switch 30.
The switch detection device provided by the embodiment comprises a current sampling circuit, a driving circuit and a control circuit, wherein the current sampling circuit is connected with a bus, the driving circuit is connected with a change-over switch, the control circuit is respectively connected with the current sampling circuit and the driving circuit, the control circuit can acquire a driving signal provided by the driving circuit to a thyristor, acquire a first current signal before the change-over switch receives the driving signal and a second current signal after the change-over switch receives the driving signal from the current sampling circuit, and determine the on-off state of the thyristor based on the acquired driving signal, the first current signal and the second current signal, so that the on-off state of the change-over switch can be rapidly and accurately determined. Further, in the process of determining the on-off state of the thyristor, the control circuit comprehensively considers a plurality of factors of current changes of the driving signal and the power grid side current signal before and after the driving signal is received by the change-over switch, so that the judgment accuracy of the on-off state of the change-over switch can be improved. As described above, the on-off or off state of the thyristor plays a critical role in the grid-connected or grid-connected switching process of the power system. In the embodiment of the application, the switch detection device can rapidly and accurately determine the on-off state of the change-over switch, and then the safety and reliability of the power system can be improved. Furthermore, the current sampling circuit of the switch detection device can be reused as the current sampling circuit in the power system, so that the cost can be reduced.
In one embodiment, the control circuit 430 can obtain whether the driving signal provided by the driving circuit 420 to the switch 30 is normal, and whether the current change of the grid-side current signal before and after the switch 30 receives the driving signal is normal, so as to determine the on-off state of the switch 30. Specifically, the control circuit 430 may determine, by sampling the driving signal, a frequency duty ratio of the driving signal, and determine that the driving signal is normal when the frequency duty ratio meets a preset threshold; and under the condition that the frequency duty ratio does not accord with a preset threshold value, determining that the driving signal is abnormal.
The control circuit 430 may also determine whether the grid-side current is normal based on the first current signal and the second current signal. Specifically, the first current signal may be a current signal acquired by current sampling current before the driving signal is supplied to the changeover switch 30. The second current signal may be a current signal acquired by current sampling after the driving signal is stably supplied to the switching switch 30. The control circuit 430 determines the amount of change between the two current signals based on the acquired first current signal and second current signal, and determines that the grid-side current signal is normal if the amount of change exceeds a threshold range; and determining that the power grid side current signal is abnormal under the condition that the variation is in the threshold range. Specifically, under normal conditions, the first current signal on the grid side should be 0 or a rated current value before the driving circuit 420 outputs the driving signal to the changeover switch 30; after the driving circuit 420 outputs the driving signal to the changeover switch 30, the second current signal on the grid side should rise to the rated current value or fall to 0 for a certain time (related to the latter stage load characteristic, thyristor zero crossing off). Wherein the threshold range may be a rated current value range.
The control circuit 430 may determine the on state of its switching switch 30 based on the determination result of the drive signal and the determination result of the current variation amount. Specifically, the control circuit 430 may determine that the changeover switch 30 is in the on state in the case where the driving signal is normal and the amounts of change in the first current signal and the second current signal exceed a preset range (the grid-side current signal is normal). In addition, the control circuit 430 may determine that the changeover switch 30 is in the off state in the case where the amounts of change in the first current signal and the second current signal are within a preset range (the grid-side current signal is abnormal).
In this embodiment, the control circuit comprehensively considers whether the driving signal is normal or not and whether the current variation on the power grid side is normal or not, and determines the on-off state of the switch based on a plurality of factors such as a determination result of the driving signal and a determination result of the current variation, so that the accuracy of determining the on-off state of the switch can be improved. Therefore, the situation that the on-off state judgment error of the change-over switch is caused by considering only a single factor (for example, a driving signal or the current change quantity at the power grid side) can be avoided, and the safety and the reliability of the power system are further improved.
In one embodiment, the control circuit 430 may include a micro control unit (Microcontroller Unit, MCU) that can obtain whether the driving signal provided by the driving circuit 420 to the switch 30 is normal, and whether the current change of the grid-side current signal before and after the switch 30 receives the driving signal is normal, so as to determine the on-off state of the switch 30. Optionally, the control circuit 430 may further include a controller and a hardware logic gate circuit (not shown in the figure), for example, the hardware logic gate circuit may include a driving signal determination circuit and a current signal determination circuit.
The drive signal determination circuit may include an RC filter circuit, a first comparator. The RC filter circuit can perform filtering processing on the received driving signal, and the cut-off frequency of the RC filter circuit is extremely low, for example, the cut-off frequency is a few hertz. One input end of the first comparator can be connected with the output end of the RC filter, the other input end of the first comparator can receive the driving reference signal, the output end of the first comparator can output a first level signal to the controller based on the received driving signal after filtering processing and the driving reference signal, and the controller can determine whether the driving signal is normal or not based on the first level signal. Wherein the drive threshold may be determined by a level complex amplitude and a duty cycle of the drive signal. Illustratively, if the first comparator outputs a high level signal, it indicates that the driving signal is normal; if the first comparator outputs a low level signal, it indicates that the driving signal is abnormal. Alternatively, if the first comparator outputs a low level signal, it indicates that the driving signal is normal; if the first comparator outputs a high level signal, it indicates that the driving signal is abnormal. In the embodiment of the present application, the driving signal determining circuit is not limited to the above-described example, but may be other forms of hardware logic circuits.
The current signal determining circuit may also include a second comparator, where an input end of the second comparator receives the current variation, and the other end of the second comparator may receive the current reference signal, and an output end of the second comparator is connected to the controller, and the second comparator may output a second level signal to the controller based on the received current variation and the current reference signal. If the positive input end of the comparator receives the current reference signal, the current reference signal is slightly greater than the bias level of the current sampling circuit 410; if the negative input of the comparator receives the current reference signal, the current reference signal is slightly less than the bias level of the current sampling circuit 410. Further, the current reference signal may be further determined based on the scaling factor of the current sampling circuit 410 and the demand determination time, which is determined by the load of the later stage of the power system, and is generally within the power frequency half period. For example, if the second comparator outputs a high level signal, it indicates that the grid side current signal is normal; if the first comparator outputs a low level signal, the first comparator indicates that the current signal at the power grid side is abnormal. Optionally, if the first comparator outputs a low-level signal, the signal indicates that the current signal at the grid side is normal; if the first comparator outputs a high level signal, the first comparator indicates that the current signal at the power grid side is abnormal. In the embodiment of the present application, the current signal determining circuit is not limited to the above-mentioned example, but may be other forms of hardware logic circuits.
In this embodiment, the control circuit may include an MCU, or may include a hardware logic circuit, which may determine, by using a software or hardware manner, whether a driving signal provided by the driving circuit to the switch is normal, and whether a current change of a current signal on the power grid side before and after the switch receives the driving signal is normal, so as to accurately and quickly determine an on-off state of the switch.
As shown in fig. 2, in one embodiment, the switch detection device 40 may include a current sampling circuit 410, a driving circuit 420, a control circuit 430, an excitation circuit 440, and a detection circuit 450, wherein the detection circuit 450 is connected to the excitation circuit 440. The two output terminals of the excitation circuit 440 are respectively connected to the bus bars on both sides of the changeover switch 30. It will be appreciated that the excitation circuit 440 may provide excitation signals to the bus bars on either side of the transfer switch 30 under the control of the control circuit 430. The detection circuit 450 may be used to detect the current value on the primary side of the excitation circuit 440. It will be appreciated that the primary and secondary sides of the excitation circuit 440 are isolated.
The control circuit 430 is also connected to the excitation circuit 440 and the detection circuit 450, respectively. The control circuit 430 may control the exciting circuit 440 to provide the exciting signal to the bus under the condition that the driving signal is normal and the variation amounts of the first current signal and the second current signal exceed the threshold range, and on the basis of this, the control circuit 430 may further determine the on-off state of the switch 30 according to the obtained current value of the primary side of the exciting circuit 440.
In this embodiment, the switch detection device further includes an excitation circuit and a detection circuit, where the control circuit can freely control the excitation circuit to provide an excitation signal to the bus, so as to implement input of the excitation circuit to the bus. Correspondingly, the control circuit can freely control the excitation circuit to stop providing the excitation signal to the bus so as to realize that the excitation circuit exits from the bus. In addition, the switch detection device can be combined with the current value of the primary side of the excitation circuit to determine the on-off state of the change-over switch, and the judgment accuracy of the on-off state of the change-over switch can be further improved.
In one embodiment, when the excitation circuit 440 is controlled by the control circuit 430 to input the bus, an excitation signal (e.g., a dc voltage) is applied to both sides of the switch 30, and when the switch 30 is in an off state, the detection circuit is turned off, and the primary side of the excitation circuit 440 is substantially free of current, or the detected current value is very small. When the switch 30 is in the closed state, a closed detection loop can be formed, the direct current excitation can be regarded as a full-load working condition, and the primary current is close to the excitation threshold (or maximum value) at the moment, so that the on-off state of the switch 30 can be judged. Specifically, the control circuit 430 is further configured to determine that the change-over switch 30 is in an off state when the driving signal is normal, the amounts of change of the first current signal and the second current signal exceed the threshold range, and the current value on the primary side of the excitation circuit 440 does not satisfy the preset condition. Accordingly, the control circuit 430 is further configured to determine that the switch 30 is in the on state when the driving signal is normal, the variation amounts of the first current signal and the second current signal exceed the threshold range, and the current value of the primary side of the excitation circuit 440 meets the preset condition. The preset condition may be that the difference between the current value of the primary side and the excitation threshold is within a preset range, for example, the current value of the primary side is close to the excitation threshold. Wherein the excitation threshold is related to the excitation voltage, loop impedance and thyristor conduction voltage drop in the excitation signal. For example, the actuation threshold may be the ratio of the difference between the applied actuation voltage and the on-voltage drop to the loop impedance.
In this embodiment, the control circuit may determine the on-off state of the switch based on a current value of the primary side of the excitation circuit, a normal driving signal, a first current signal, and a second current signal, where the on-off state of the switch may be determined when the driving signal is normal, the amounts of change of the first current signal and the second current signal exceed a threshold range, and the current value of the primary side of the excitation circuit is a current value that does not satisfy a preset condition. Correspondingly, the control circuit can determine that the change-over switch is in a conducting state when the driving signal is normal, the variation of the first current signal and the second current signal exceeds the threshold range and the current value of the primary side of the excitation circuit meets the preset condition, so that the judgment accuracy of the on-off state of the change-over switch can be further improved, and the safety and reliability of the power system are improved.
As shown in fig. 3, in one embodiment, the excitation circuit 440 includes: an excitation power source 441 and an excitation switching unit 443. Wherein the excitation power source 441 is configured to provide an excitation signal. The excitation power source 441 may be an isolated voltage source. The excitation switch unit 443 is connected to the excitation power source 441, the bus bars on both sides of the switch 30, and the control circuit 430, and is turned on by the control circuit 430 to transmit an excitation signal to the bus bars.
The excitation switch unit 443 may include a first switch K1 and a second switch K2, wherein a first end of the first switch K1 is connected to the excitation power source 441, and a second end of the first switch K1 is connected to a bus bar on one side of the switching switch 30; the first end of the second switch K2 is connected to the excitation power source 441, and the second end of the second switch K2 is connected to the bus bar on the other side of the changeover switch 30. Further, a second end of the first switch K1 is connected to one terminal of the switch 30, and a second end of the second switch K2 is connected to the other terminal of the switch 30. Taking the change-over switch 30 as a thyristor for illustration, two outputs of the excitation circuit 440 are respectively connected to a first pole and a second pole of the thyristor, and an excitation signal can be provided to the thyristor under the control of the control circuit 430. In this way, the driving power of the driving circuit 420 can be multiplexed with the exciting power source 441, and the cost can be reduced.
Alternatively, the first switch K1 and the second switch K2 may be single pole single throw switches, or may be relays, circuit breakers, or the like. Alternatively, the excitation switch unit 443 may also be a double pole double throw switch. In the embodiment of the present application, the switch types of the excitation switch unit 443, the first switch K1, and the second switch K2 are not limited.
In one embodiment, the control circuit 430 is further configured to determine a fault type of the power system according to the driving signal, the first current signal, the second current signal, and the on-off state of the exciting switch unit 443 based on any of the foregoing embodiments. Specifically, the control circuit 430 may determine the fault type of the power system based on whether the driving signal is normal, whether the grid-side current signal is normal, and the on-off state of the exciting switching unit 443. The fault types include, among others, a change-over switch 30 fault, a current sampling circuit 410 fault, a detection circuit 450 fault, and a drive circuit 420 fault. The switch 30 failure indicates a thyristor body or drive signal to thyristor junction line failure. The current sampling circuit 410 failure represents the current sampling circuit 410 or a sampling loop failure where the current sampling circuit 410 is located. The detection circuit 450 failure indicates an excitation detection loop failure where the excitation power source 441 is located. The failure of the driving circuit 420 indicates that the driving circuit 420 is failed, or that the circuit in which the driving circuit 420 is located is failed.
Specifically, the control circuit 430 may determine that the changeover switch 30 fails in the case where the driving signal is normal, the amounts of change in the first current signal and the second current signal are within the threshold value range, and the exciting switch unit 443 is in the off state. For example, a thyristor body or drive signal to thyristor connection line fault may be determined.
The control circuit 430 may determine that the current sampling circuit 410 fails in a case where the driving signal is normal, the variation amounts of the first current signal and the second current signal are within the threshold range, and the exciting switching unit 443 is in the on state. For example, current sampling circuit 410 or a sampling loop fault in which current sampling circuit 410 is located may be determined.
The control circuit 430 may determine that the detection circuit 450 is malfunctioning in the case where the driving signal is normal, the variation amounts of the first current signal and the second current signal exceed the threshold range, and the excitation switching unit 443 is in an off state. For example, an excitation detection loop fault may be determined where the excitation power source 441 is located.
The control circuit 430 may determine that the driving circuit 420 fails in the case where the driving signal is abnormal, the variation amounts of the first current signal and the second current signal exceed the threshold range, and the exciting switching unit 443 is in an off state.
Alternatively, the control circuit 430 may determine that a fault may occur at a plurality of locations in the event of an abnormal driving signal, an abnormal grid current sampling, and an excitation switch unit 443 being closed.
Alternatively, the control circuit 430 may drive the signal abnormally, and in the case that the grid current sampling is normal and the excitation switch unit 443 is closed, it may be determined that the excitation switch unit 443 is triggered and the driving circuit fails.
In this embodiment, the switch detection device not only can quickly and accurately determine the on-off state of the change-over switch, but also can determine the fault type of the power system based on the driving signal, the first current signal, the second current signal and the on-off state of the excitation switch unit, and can realize the accurate positioning of the fault, so that the remote maintenance and troubleshooting of the fault problem are facilitated, corresponding countermeasures are made, the response to the fault can be quickly made, the expansion of the accident is avoided, the maintenance efficiency is improved, the maintenance cost is reduced, and the reliability of the power system is also improved.
With continued reference to fig. 1, an embodiment of the present application further provides an electric power system, which includes an energy storage system 10, an electric power network 20, a change-over switch 30, and a switch detection device 40 according to any of the foregoing embodiments. In the power system, by providing the switch detection device 40, it includes a current sampling circuit 410, a driving circuit 420, and a control circuit 430. The control circuit 430 may determine the on-off state of the thyristor based on the acquired driving signal, the first current signal and the second current signal, which may quickly and accurately determine the on-off state of the switch 30. Further, in determining the on-off state of the thyristor, the control circuit 430 comprehensively considers a plurality of factors of the driving signal and the current change of the power grid side current signal before and after the driving signal is received by the switch 30, so that the accuracy of judging the on-off state of the switch 30 can be improved. Because the on-off or off-state of the thyristor plays a key role in the off-grid switching or in-grid switching process of the power system, based on the key role, the accurate judgment of the on-off state of the change-over switch 30 can improve the safety and reliability of the power system.
As shown in fig. 4, in one embodiment, the energy storage system 10 includes: the power supply device comprises an inverter 110, an energy storage converter 120 and a switch circuit 130, wherein a first end of the switch circuit 130 is connected with the bus, and a plurality of second ends of the switch circuit 130 are respectively connected with the inverter 110, the energy storage converter 120 and a load 140 correspondingly. Wherein the switching circuit 130 may include a plurality of circuit breakers. By way of example, the switching circuit 130 may include a first breaker QF1, a second breaker QF2, and a third breaker QF3, wherein a first end of the first breaker QF1 is connected to the bus bar, a second end of the first breaker QF1 is connected to the inverter 110, a first end of the second breaker QF2 is connected to the bus bar, a second end of the second breaker QF2 is connected to the energy storage converter 120, a first end of the third breaker QF3 is connected to the bus bar, and a second end of the third breaker QF3 is connected to the load. When the third breaker QF3 is in a conducting state, the load operation of the power system is indicated; when the third circuit breaker QF3 is in the open state, no load operation of the power system is indicated. In the embodiment of the present application, the on-off of each breaker may be controlled by the control circuit 430, or may be controlled by a controller of the power system.
When the power system is switched on-load and off-grid (grid-connected and off-grid), the switch detection device 40 may be configured to determine the on-off state of the switch 30 according to the driving signal, the first current signal and the second current signal. Alternatively, the switch detection device 40 may be configured to determine the on-off state of the switch 30 according to the driving signal, the first current signal and the second current signal when the power system is switched off-grid (off-grid cut-grid). It will be appreciated that the excitation circuit 440 in the switch detection device 40 may not be added to the bus bar at an initial stage when the load is on-load and off-grid or off-grid. The switch detection device 40 may be configured to determine the on-off state of the switch 30 according to the driving signal, the first current signal and the second current signal, and the specific determination process thereof may refer to the foregoing embodiment, which is not described herein.
In one embodiment, in the case that the switch detection device 40 includes the excitation circuit 440 and the detection circuit 450, and the power system is in load and off-grid or off-grid, the driving signal is normal, the variation of the first current signal and the second current signal is within the threshold range, the switch detection device 40 is further configured to control the excitation circuit 440 to provide the excitation signal to the bus, and determine the on-off state of the switch 30 according to the obtained current value of the primary side of the excitation circuit 440.
For convenience of explanation, as shown in fig. 5, the switch detection device 40 includes a current sampling circuit 410, a driving circuit 420, a control circuit 430, an excitation circuit 440, and a detection circuit 450, and an electrical system thereof is exemplified.
As shown in fig. 6, in the case of on-load, the implementation process of off-grid-cut grid connection is specifically as follows:
first, it is determined whether the power grid is abnormal, and if the power grid is normal, the grid-connected operation is continued, and if the power grid is abnormal, the driving circuit 420 outputs a driving signal (off signal) to the changeover switch 30. The control circuit 430 determines whether the driving signal is normal, if the driving signal is abnormal, determines that the driving circuit 420 is malfunctioning, and if the driving signal is normal, the control circuit 430 determines whether the grid-side current signal is normal based on the acquired first current signal and second current signal. In the case of abnormal current signal at the power grid side, the control circuit 430 controls the exciting circuit 440 to provide the exciting signal to the bus, further, the control circuit 430 may compare the current value at the primary side of the exciting circuit 440 with the exciting threshold, and determine that the current signal at the power grid side is abnormal in the case that the current value at the primary side of the exciting circuit 440 is far less than the exciting threshold (determined to be valid); when the current value on the primary side of the excitation circuit 440 is close to the excitation threshold (determined to be invalid), an off failure of the changeover switch 30 is determined, and the changeover switch is actually in the on state. Wherein the excitation threshold is related to the excitation voltage, loop impedance and thyristor conduction voltage drop in the excitation signal. For example, the actuation threshold may be the ratio of the difference between the applied actuation voltage and the on-voltage drop to the loop impedance.
Optionally, under the condition that the current signal at the power grid side is normal, the judgment of the off-grid condition can be further executed so as to realize the off-grid switching. The off-grid condition judgment may include whether the inverter 110 and/or the energy storage converter 120 in the energy storage system 10 support an off-grid condition, and in the case of supporting the off-grid condition, the working mode of the inverter 110 and/or the energy storage converter 120 is switched to be switched to an off-grid working mode (for example, a VF or VSG mode), so as to control the disconnection of the contactor on the bus, and detect whether the corresponding contactor is disconnected, and implement the off-grid switching in the case that the contactor is disconnected. Alternatively, if the inverter 110 and the energy storage converter 120 in the energy storage system 10 do not support off-grid conditions, the off-grid switching fails. Alternatively, in the event that the contactor is not opened, a fault may be reported.
In this embodiment, when the on-load and off-grid switching is performed, the excitation circuit 440 may not need to add a bus at the initial stage, and when the driving signal is normal but the current signal on the power grid side is abnormal, the excitation circuit 440 may be controlled to provide the excitation signal to the bus, and the on-off state of the switch 30 may be determined again by combining the current value on the primary side of the excitation circuit 440, so that the accuracy of the on-off state of the switch 30 may be improved, and in addition, the fault type (or fault position) of the power system may be further determined.
As shown in fig. 7, in the case of load, the implementation process of grid-connected and off-grid is specifically as follows:
firstly, determining whether a grid-connected condition is met, and continuously waiting for a grid-connected instruction under the condition that the grid-connected condition is not met; and controlling the suction contactor under the condition that the grid-connected condition is met. Then, detecting whether the contactor is attracted or not, and reporting a fault if the contactor is not attracted; if the contactor is normally engaged, it is continuously determined whether the power network 20 and the energy storage system 10 on both sides of the change-over switch 30 are synchronous, and if not, the electrical parameters of the inverter 110 and/or the energy storage converter 120 of the energy storage system 10, such as voltage, phase, frequency, are correspondingly adjusted. In the case where the power network 20 and the energy storage system 10 on both sides of the switch 30 are synchronized, the driving circuit 420 outputs a driving signal (on signal) to the switch 30. The control circuit 430 determines whether the driving signal is normal, and if the driving signal is abnormal, determines that the driving circuit 420 is faulty; if the driving signal is normal, the control circuit 430 determines whether the grid-side current signal is normal based on the acquired first current signal and second current signal. In the case of an abnormal current signal on the grid side, the control circuit 430 controls the exciting circuit 440 to provide an exciting signal to the bus, further, the control circuit 430 may compare the current value on the primary side of the exciting circuit 440 with an exciting threshold, and determine that the current signal on the grid side is abnormal in the case that the current value on the primary side of the exciting circuit 440 is close to the exciting threshold (determined to be valid), and determine that the change-over switch 30 is on in the case that the current value on the primary side of the exciting circuit 440 is far less than the exciting threshold (determined to be valid), and that the change-over hanger is actually in an off state.
Optionally, under the condition that the current signal at the grid side is normal, the operation modes of the inverter 110 and the energy storage converter 120 are switched to the grid-connected operation mode (for example, the PQ mode) so as to realize the grid-off switching.
In this embodiment, when the on-load and off-grid switching is performed, the excitation circuit 440 may not need to add a bus at the initial stage, and when the driving signal is normal but the current signal on the power grid side is abnormal, the excitation circuit 440 may be controlled to provide the excitation signal to the bus, and the on-off state of the switch 30 may be determined again by combining the current value on the primary side of the excitation circuit 440, so that the accuracy of the on-off state of the switch 30 may be improved, and in addition, the fault type (or fault position) of the power system may be further determined.
In one embodiment, in the case that the switch detection device 40 includes the excitation circuit 440 and the detection circuit 450, and the power system is not loaded and switched off-grid, the switch detection device 40 is further configured to control the excitation circuit 440 to provide an excitation signal to the bus, and determine the on-off state of the switch 30 according to the obtained current value at the primary side of the excitation circuit 440.
For convenience of explanation, the switch detection device 40 includes a current sampling circuit 410, a driving circuit 420, a control circuit 430, an excitation circuit 440, and a detection circuit 450, and an electrical system thereof is exemplified as no load.
In the case of off-grid switching of the power system without load, the switch detection device 40 needs to control the excitation circuit 440 to be put into operation on the bus before judging the state of the switch 30, and judges the state of the switch 30 by detecting the current of the applied excitation source.
Under the condition that the power system is not loaded and is switched off the grid, the abnormal detection of the current signal at the power grid side is changed into the judgment of the current value and the excitation threshold value at the primary side of the excitation circuit, and the rest processes are basically consistent with the control process of the loaded and off-grid switching, so that the description is omitted.
In one embodiment, the switch detection device 40 may further output a corresponding fault command to the energy storage system 10 to stop the energy storage system 10 when it is determined that the power system fails. Specifically, the control circuit 430 may determine the fault type of the power system according to the driving signal, the first current signal, the second current signal, and the on-off state of the exciting switch unit 443. When the fault type of the power system is determined, a corresponding fault instruction may be output to the energy storage system 10, so that the energy storage system 10 stops working. Specifically, the control circuit 430 may output a fault instruction to the inverter 110 and the energy storage converter 120 of the energy storage system 10 when determining the fault type of the power system, so that the inverter 110 and the energy storage converter 120 perform wave-sealing processing, which may quickly respond to the fault state, avoid the expansion of an accident, and improve the safety and reliability of the power system.
In the description of the present specification, reference to the term "some embodiments," "other embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples merely represent several embodiments of the present application, the description of which is more specific and detailed and which should not be construed as limiting the scope of the present application in any way. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.
Claims (12)
1. The switch detection device of the power system is characterized in that the power system comprises an energy storage system, a power network and a change-over switch, wherein the energy storage system is connected with the power network through a bus, and the change-over switch is connected in series with the bus; wherein, the switch detection device includes:
the current sampling circuit is connected with the bus and used for collecting current signals of the power network side;
the driving circuit is connected with the change-over switch and used for providing a driving signal to the change-over switch so as to control the on-off state of the change-over switch;
the control circuit is respectively connected with the current sampling circuit and the driving circuit and is used for respectively acquiring a first current signal before the driving signal is provided to the change-over switch and a second current signal after the driving signal is provided to the change-over switch, and determining the on-off state of the change-over switch according to the driving signal, the first current signal and the second current signal.
2. The switch detection device according to claim 1, wherein the control circuit is further configured to determine that the change-over switch is in an on state in a case where the drive signal is normal and the amounts of change of the first current signal and the second current signal exceed a threshold range;
The control circuit is further configured to determine that the change-over switch is in an off state when the amounts of change of the first current signal and the second current signal are within the threshold range.
3. The switch detection device according to claim 1, characterized in that the switch detection device further comprises:
the two output ends of the excitation circuit are respectively and correspondingly connected with buses on two sides of the change-over switch;
the detection circuit is connected with the excitation circuit and is used for detecting the current value of the primary side of the excitation circuit; wherein,
the control circuit is also respectively connected with the excitation circuit and the detection circuit and is used for controlling the excitation circuit to provide an excitation signal to the bus and determining the on-off state of the change-over switch according to the acquired current value of the primary side of the excitation circuit under the condition that the driving signal is normal and the variation of the first current signal and the second current signal exceeds a threshold range.
4. The switch detection device according to claim 3, wherein the control circuit is further configured to determine that the change-over switch is in an off state in a case where the drive signal is normal, the amounts of change of the first current signal and the second current signal exceed a threshold range, and the current value on the primary side of the excitation circuit does not satisfy a preset condition; and the control circuit is further used for determining that the change-over switch is in a conducting state under the condition that the driving signal is normal, the variation of the first current signal and the second current signal exceeds a threshold range and the current value of the primary side of the excitation circuit meets a preset condition.
5. A switch detection arrangement according to claim 3, wherein the excitation circuit comprises:
an excitation power supply for providing the excitation signal;
and the excitation switch unit is respectively connected with the excitation power supply, buses at two sides of the change-over switch and the control circuit and is used for conducting under the action of the control circuit so as to transmit the excitation signal to the buses.
6. The switch detection device of claim 5, wherein the control circuit is further configured to determine a fault type of the power system based on the drive signal, the first current signal, the second current signal, and the on-off state of the excitation switch unit, wherein the fault type includes a diverter switch fault, the current sampling circuit fault, the detection circuit fault, and the drive circuit fault.
7. The switch detection device of claim 6, wherein the control circuit is further configured to:
determining that the change-over switch has a fault when the driving signal is normal, the variation of the first current signal and the second current signal is within the threshold range, and the excitation switch unit is in an off state;
Determining that the current sampling circuit is faulty when the driving signal is normal, the variation amounts of the first current signal and the second current signal are within the threshold range, and the excitation switch unit is in a conducting state;
determining that the detection circuit is faulty when the driving signal is normal, the variation of the first current signal and the second current signal exceeds a threshold range, and the excitation switch unit is in an off state;
and determining that the driving circuit is faulty when the driving signal is abnormal, the variation of the first current signal and the second current signal exceeds a threshold range, and the excitation switch unit is in an off state.
8. An electrical power system, comprising: energy storage system, power network, change-over switch and switch detection device according to any one of claims 1-7.
9. The power system of claim 8, wherein the energy storage system comprises: the power supply device comprises an inverter, an energy storage converter and a switch circuit, wherein a first end of the switch circuit is connected with a bus, and a plurality of second ends of the switch circuit are correspondingly connected with the inverter, the energy storage converter and a load respectively; wherein,
When the power system is in load and off-grid switching, the switch detection device is used for determining the on-off state of the switching switch according to the driving signal, the first current signal and the second current signal.
10. The power system according to claim 9, wherein when the switch detection device includes an excitation circuit and a detection circuit, and the driving signal is normal, the amounts of change of the first current signal and the second current signal are within a threshold range when the power system is in load and off-grid switching, the switch detection device is further configured to control the excitation circuit to provide an excitation signal to the bus, and determine the on-off state of the switch according to the obtained current value of the primary side of the excitation circuit.
11. The power system of claim 9, wherein in the case that the switch detection device includes an excitation circuit and a detection circuit, and the power system is switched off-grid without load, the switch detection device is further configured to control the excitation circuit to provide an excitation signal to the bus, and determine the on-off state of the switch according to the obtained current value of the primary side of the excitation circuit.
12. The power system of claim 8, wherein the switch detection device is further configured to output a fault command to the energy storage system to deactivate the energy storage system in the event of a failure of the power system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311781127.7A CN117741425A (en) | 2023-12-22 | 2023-12-22 | Switch detection device of power system and power system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311781127.7A CN117741425A (en) | 2023-12-22 | 2023-12-22 | Switch detection device of power system and power system |
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| CN117741425A true CN117741425A (en) | 2024-03-22 |
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| CN202311781127.7A Pending CN117741425A (en) | 2023-12-22 | 2023-12-22 | Switch detection device of power system and power system |
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| Country | Link |
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| CN (1) | CN117741425A (en) |
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