CN109031180B - Method and device for detecting residual voltage state of capacitor voltage transformer - Google Patents
Method and device for detecting residual voltage state of capacitor voltage transformer Download PDFInfo
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Abstract
The invention relates to a method and a device for detecting the residual voltage state of a capacitor voltage transformer, wherein the method comprises the following steps: acquiring first differential values of at least one group of adjacent first sampling signals at the output end of one capacitor voltage transformer; and determining whether the capacitor voltage transformer is in a residual voltage state or not according to each group of the first differential values. According to the invention, whether the capacitor voltage transformer is in a residual voltage state or not can be quickly determined.
Description
Technical Field
The invention relates to the field of power systems, in particular to a method and a device for detecting a residual voltage state of a capacitor voltage transformer.
Background
A Capacitor voltage Transformer (CPT) is often used in a high-voltage power grid to monitor a voltage signal on a primary side (high-voltage side) of the power grid. Fig. 1 shows a schematic diagram of a typical capacitive voltage transformer. As shown in fig. 1, a capacitor voltage transformer CPT 10 is connected between a primary (primary) device 20 and a Secondary (Secondary) device 30 in the power system, and is configured to convert the obtained primary high voltage Uprim into a Secondary low voltage Usec, and send the Secondary low voltage Usec to the Secondary device 30 for further analysis. Here, the primary-side device 20 is a device for generating and using electric energy, such as a high-voltage power transmission cable, a high-voltage switch, a transformer, a reactor, or the like. The secondary equipment 30 is mainly equipment for monitoring, measuring, controlling, protecting or adjusting primary equipment in the power system, such as a merging unit and relay protection equipment.
In fig. 1, the input A, B of the CPT 10 is connected to the primary-side device 20, i.e. a primary-side high voltage Uprim is obtained, e.g. on a high-voltage network line. The CPT 10 includes two sensing capacitors C1 and C2 connected in series. In terms of capacitance capacity, the capacitance C1 and the capacitance C2 may be of the order of nF or pF, the ratio of which is determined, for example, from the ratio between Uprim and Usec. The transformer 10 has its output C, D taken across capacitor C2. For example, if the primary side voltage Uprim to which the input terminal A, B is connected is 110kV, the secondary side voltage Usec between the output terminals C, D may reach about 100V. Usec is output to secondary 30 for analysis and processing. Such a capacitive voltage transformer is also referred to as a contactless voltage transformer.
In the CPT 10 shown in fig. 1, Uprim is generally a sinusoidal ac signal, and Usec varies with Uprim. However, due to the presence of the induced capacitance, Usec lags Uprim. The primary-side device 20 may be suddenly turned off in various cases. For example, when a fault occurs, the primary-side device may suddenly turn off at a time point when Uprim ≠ 0, causing Uprim to momentarily set to zero. At this time, due to the presence of the sense capacitance, Usec cannot instantaneously become zero. In contrast, residual charge accumulates on the sensing capacitors C1 and C2, which appears as Usec held at a dc voltage, also referred to as residual voltage Vtrap. For this reason, the residual charge is also referred to as a residual voltage state (trap charge). If there is no charge discharging circuit in the primary-side device 20, the residual voltage Vtrap is maintained until the primary-side device 20 is turned on again. Since the residual voltage is applied to the output C, D, when the primary device 20 is turned back on, the secondary device 30 will likely sense a false Usec and therefore take the protective action in the hope of a fault. It follows that the presence of residual charges is very dangerous.
Therefore, how to determine whether the primary side is disconnected in time becomes an urgent problem to be solved.
Disclosure of Invention
In view of the above, the present invention provides a method and an apparatus for detecting a residual voltage state of a capacitive voltage transformer, so as to quickly detect whether a primary side is disconnected.
The invention provides a method for detecting the residual voltage state of a capacitor voltage transformer on the one hand, which comprises the following steps:
acquiring first differential values of at least one group of adjacent first sampling signals at the output end of one capacitor voltage transformer;
and determining whether the capacitor voltage transformer is in a residual voltage state or not according to each group of the first differential values.
First differential values corresponding to at least one group of adjacent first sampling signals are obtained, and whether the capacitor voltage transformer is in a residual voltage state or not is determined according to the first differential values of the groups. The judgment process is simple, and a mode of acquiring the differential value of the sampling signal and performing related judgment can be adopted, so that the device has high response speed, the residual voltage state of the capacitor voltage transformer can be determined in time, and whether the primary side switch is disconnected or not can be determined in time.
According to the method as described above, optionally, determining whether the capacitor voltage transformer is in a residual voltage state according to each group of the first differential values includes:
and in a continuous preset time period, if the absolute value of a first difference value between two first differential values in each group is judged to be smaller than a first preset threshold value and the absolute value of each first differential value is judged to be smaller than a second preset threshold value, determining that the capacitor voltage transformer is in a residual voltage state.
After the first differential values of two adjacent first sampling signals are obtained, whether the first sampling signals are in a stable state or not is determined according to the absolute value of the difference value of the first differential values, the stable state of the first sampling signals is verified according to the absolute value of the first differential values of the first sampling signals, and the residual voltage state of the capacitor voltage transformer can be determined timely and accurately.
According to the method, optionally, after determining that the absolute values of the first differences between two first differential values in each group are all smaller than a first preset threshold, and the absolute values of the first differential values are all smaller than a second preset threshold, and before determining that the capacitor voltage transformer is in a residual voltage state, the method further includes:
judging whether a second difference value between the maximum one and the minimum one of the first differential values is smaller than a third preset threshold value within the preset time period;
and if so, executing the operation of determining that the capacitor voltage transformer is in the residual voltage state.
The tolerance to sampling errors is increased in consideration of the dc offset of the front-end sampling loop. Therefore, the final judgment result can be more accurate.
According to the method as described above, optionally, before obtaining the first differential values of at least one group of adjacent first sampling signals at the output terminal of one capacitor voltage transformer, the method further includes:
judging whether the absolute value of a third difference value between second differential values of two adjacent second sampling signals at the output end of the capacitor voltage transformer is smaller than a fourth preset threshold value or not, and whether the absolute values of the two second differential values are both smaller than a fifth preset threshold value or not;
and if the judgment results are yes, performing operation of acquiring first differential values of at least one group of adjacent first sampling signals at the output end of one capacitor voltage transformer.
The method comprises the steps of firstly determining an initial condition for detecting the residual voltage state of the capacitor voltage transformer, and when the condition is met, executing subsequent steps to determine whether the capacitor voltage transformer is in the residual voltage state, so that the process can be saved, and the burden of the device can be reduced.
According to the method as described above, optionally, after determining that there is a third difference between the second differential values of two adjacent second sampling signals at the output end of the capacitor voltage transformer, and before performing the operation of obtaining the first differential values of at least one group of adjacent first sampling signals at the output end of the capacitor voltage transformer, the method further includes:
and determining whether the absolute values of the second integral values corresponding to the two second sampling signals are both greater than a sixth preset threshold, and if so, executing the operation of acquiring at least one group of adjacent first sampling signals at the output end of the capacitor voltage transformer.
The capacitor voltage transformer is further verified to be in a residual voltage state by determining that the input end of the capacitor voltage transformer has an input and the switch of the capacitor voltage transformer is switched from an on state to an off state.
According to the method, optionally, after determining that the absolute values of the second integrated values corresponding to the two second sampling signals are both greater than a sixth preset threshold, before performing the operation of acquiring at least one group of adjacent first sampling signals at the output end of the capacitor voltage transformer, the method further includes:
determining whether the absolute values of the two second integrated values are in a decreasing trend with time;
and if the determination result is yes, performing operation of acquiring at least one group of adjacent first sampling signals of the output end of the capacitor voltage transformer.
And two adjacent integrated values show a decreasing trend, which indicates that the amplitude of the second sampling signal is decreasing, and further verifies that the capacitor voltage transformer is in a residual voltage state.
According to the method, optionally, the preset time period T is T/4 < T ≦ T/2, where T is a system period of a system in which the capacitor voltage transformer is located.
Another aspect of the present invention provides an apparatus for detecting a residual voltage state of a capacitor voltage transformer, comprising:
an acquisition unit which acquires first differential values of at least one group of adjacent first sampling signals at the output end of a capacitor voltage transformer;
and a determining unit, for determining whether the capacitor voltage transformer is in residual voltage state according to each group of the first differential values.
First differential values corresponding to at least one group of adjacent first sampling signals are obtained, and whether the capacitor voltage transformer is in a residual voltage state or not is determined according to the first differential values of the groups. The judgment process is simple, and a mode of acquiring the differential value of the sampling signal and performing related judgment can be adopted, so that the device has high response speed, the residual voltage state of the capacitor voltage transformer can be determined in time, and whether the primary side switch is disconnected or not can be determined in time.
According to the apparatus as described above, optionally, the determining unit is specifically configured to:
and in a continuous preset time period, if the absolute value of a first difference value between two first differential values in each group is judged to be smaller than a first preset threshold value and the absolute value of each first differential value is judged to be smaller than a second preset threshold value, determining that the capacitor voltage transformer is in a residual voltage state.
After the first differential values of two adjacent first sampling signals are obtained, whether the first sampling signals are in a stable state or not is determined according to the absolute value of the difference value of the first differential values, the stable state of the first sampling signals is verified according to the absolute value of the first differential values of the first sampling signals, and the residual voltage state of the capacitor voltage transformer can be determined timely and accurately. According to the apparatus as described above, optionally, the determining unit includes:
a first judging subunit, configured to, within consecutive preset time periods, judge whether absolute values of first differences between two first differential values in each group are all smaller than a first preset threshold, and whether absolute values of the first differential values are all smaller than a second preset threshold, and if the judgment result is yes, trigger a second judging subunit;
the second judging subunit is configured to judge whether a second difference between a largest one and a smallest one of the first differential values in the preset time period is smaller than a third preset threshold, and if the second difference is smaller than the third preset threshold, trigger a determining subunit;
and the determining subunit is used for determining the operation that the capacitor voltage transformer is in a residual voltage state.
The tolerance to sampling errors is increased in consideration of the dc offset of the front-end sampling loop. Therefore, the final judgment result can be more accurate.
The apparatus as described above, optionally, further comprising:
and the judging unit is used for judging whether the absolute value of a third difference value between second differential values of two adjacent second sampling signals at the output end of the capacitor voltage transformer is smaller than a fourth preset threshold value or not, judging whether the absolute values of the two second differential values are smaller than a fifth preset threshold value or not, and triggering the acquiring unit if the judgment result is yes.
The method comprises the steps of firstly determining an initial condition for detecting the residual voltage state of the capacitor voltage transformer, and when the condition is met, executing subsequent steps to determine whether the capacitor voltage transformer is in the residual voltage state, so that the process can be saved, and the burden of the device can be reduced.
According to the apparatus as described above, optionally, after determining that there is a third difference between second differential values of two adjacent second sampling signals at the output end of the capacitive voltage transformer, the absolute value of the third difference being smaller than a fourth preset threshold, and before triggering the acquiring unit, the determining unit is further configured to:
and determining whether the absolute values of the second integral values corresponding to the two second sampling signals are both greater than a sixth preset threshold, and if so, triggering the acquisition unit.
The capacitor voltage transformer is further verified to be in a residual voltage state by determining that the input end of the capacitor voltage transformer has an input and the switch of the capacitor voltage transformer is switched from an on state to an off state.
According to the apparatus as described above, optionally, after determining that the absolute values of the second integrated values corresponding to the two second sampling signals are both greater than a sixth preset threshold, and before performing the operation of acquiring at least one group of adjacent first sampling signals at the output end of the capacitor voltage transformer, the determining unit is further configured to:
determining whether the absolute values of the two second integrated values are in a decreasing trend with time;
and if the determination result is yes, performing operation of acquiring at least one group of adjacent first sampling signals of the output end of the capacitor voltage transformer.
And two adjacent integrated values show a decreasing trend, which indicates that the amplitude of the second sampling signal is decreasing, and further verifies that the capacitor voltage transformer is in a residual voltage state.
According to the device, optionally, the preset time period T is T/4 < T ≦ T/2, where T is a system period of a system in which the capacitive voltage transformer is located.
Yet another aspect of the present invention provides an apparatus for detecting a residual voltage state of a capacitor voltage transformer, comprising:
at least one communication interface for communicating with the capacitive voltage transformer;
at least one memory for storing first differential values of at least one set of adjacent first sampled signals at the output of the capacitive voltage transformer;
at least one processor connected to the memory, the processor being configured to perform any of the above-mentioned methods for detecting a residual voltage state of a capacitive voltage transformer.
In yet another aspect, the present invention provides an apparatus for detecting a residual voltage state of a capacitive voltage transformer, at least one memory for storing instructions;
at least one processor configured to execute the method of detecting a residual voltage state of a capacitive voltage transformer according to any one of the preceding claims according to instructions stored in the memory.
Another aspect of the invention provides a readable storage medium having stored therein machine readable instructions which, when executed by a machine, perform a method of detecting a residual voltage condition of a capacitive voltage transformer according to any preceding claim.
Drawings
The foregoing and other features and advantages of the invention will become more apparent to those skilled in the art to which the invention relates upon consideration of the following detailed description of a preferred embodiment of the invention with reference to the accompanying drawings, in which:
fig. 1 is a schematic structural diagram of a capacitor voltage transformer according to the present invention. .
Fig. 2 is a schematic flow chart of a method for detecting a residual voltage state of a capacitive voltage transformer according to an embodiment of the invention.
Fig. 3 is a schematic flow chart of a method for detecting a residual voltage state of a capacitive voltage transformer according to another embodiment of the present invention.
Fig. 4 is a flowchart illustrating a method for detecting a residual voltage state of a capacitive voltage transformer according to another embodiment of the present invention.
FIG. 5 is a diagram illustrating a differential value and an integral value of a sampled signal according to an embodiment of the present invention.
Fig. 6 is a schematic structural diagram of an apparatus for detecting a residual voltage state of a capacitive voltage transformer according to an embodiment of the invention.
Fig. 7 is a schematic structural diagram of an apparatus for detecting a residual voltage state of a capacitive voltage transformer according to another embodiment of the present invention.
Fig. 8 is a schematic structural diagram of an apparatus for detecting a residual voltage state of a capacitive voltage transformer according to still another embodiment of the present invention.
Fig. 9 is a schematic structural diagram of an apparatus for detecting a residual voltage state of a capacitive voltage transformer according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail by referring to the following examples.
Example one
The embodiment provides a method for detecting the residual voltage state of a capacitor voltage transformer, which is mainly implemented by a device for detecting the residual voltage state of the capacitor voltage transformer. The device can be a computer, an iPad and other equipment.
Fig. 2 is a schematic flow chart of a method for detecting a residual voltage state of a capacitive voltage transformer according to the present embodiment. The method comprises the following steps:
In this embodiment, two adjacent sampling signals at the output end of the capacitor voltage transformer are used as a group of adjacent first sampling signals. In this embodiment, a plurality of such adjacent sets of first sampling signals may be acquired in successive time periods. The first sampling signal may be a current signal or a voltage signal, and may be specifically selected according to actual conditions. It should be noted that the first sampled signal has a corresponding differential value and also has a corresponding integrated value, so that a group of adjacent first sampled signals corresponds to a group of adjacent first differential values and a group of adjacent first integrated values. In general, if the first sampling signal is a voltage signal, a first integral value of the first sampling signal is output from an output end of the capacitor voltage transformer, and a corresponding first differential value needs to be obtained through calculation; if the first sampling signal is a current signal, the first differential value of the first sampling signal is directly output from the capacitor voltage transformer. It is common knowledge in the art to obtain an integral value or a differential value corresponding to a sampled signal.
Taking fig. 1 as an example, if the first sampling signal is a voltage signal, the first sampling signal may be Usec in fig. 1, the Usec is an integrated value of the first sampling signal, and a first integrated value of a plurality of discrete first sampling signals sampled continuously in time may be connected into a curve, as shown by a curve P in fig. 5, and correspondingly, a first differential value of the first sampling signal is shown by a curve Q in fig. 5. The first differential signal corresponding to the first sampling signal may be a rate of change of the corresponding P-curve over time shown in fig. 5 at the time point. It is to be noted that the physical meaning of the differential value Q is the rate of change of voltage with time, which is not in kV. In this embodiment, for the sake of comparison with the integral value P, the Q-curve represents a value obtained by converting the differential value into a corresponding voltage. That is, the Q curve reflects the correspondence relationship in which the differential value of the sampling signal is mapped onto the primary voltage. In order to make the relationship between the P-curve and the Q-curve clearer, the P-curve and the Q-curve are shown simultaneously in fig. 5.
And step 202, determining whether the capacitor voltage transformer is in a residual voltage state or not according to each group of first differential values.
Specifically, whether the capacitor voltage transformer is in a residual voltage state or not can be determined according to the variation trend of the first differential value. For example, if the variation amplitude is larger than a certain preset threshold, the capacitive voltage transformer is determined to be in the residual voltage state, or if the absolute value of the first differential value changes in a sharp descending trend along with time, the capacitive voltage transformer is determined to be in the residual voltage state. Of course, the first differential value may also be combined with other factor values to determine whether the capacitor voltage transformer is in the residual voltage state, which is not described in detail herein.
Optionally, the step may comprise: and in a continuous preset time period, if the absolute value of the first difference value of the two first differential values in each group is judged to be smaller than a first preset threshold value and the absolute value of each first differential value is smaller than a second preset threshold value, determining that the capacitor voltage transformer is in a residual voltage state. The preset time period may be set empirically. The absolute value of the difference value of the two first differential values in each group is smaller than a first preset threshold, which indicates that the change amplitude of the first sampling signal is smaller, namely, the first sampling signal is in a stable state; and if the absolute values of the two first differential values in each group are smaller than a second preset threshold, further determining that the first sampling signal is in a stable state. Within a continuous preset time period, the first differential value of the first sampling signal is always in a stable state, so that the condition that the capacitor voltage transformer is in a residual voltage state can be indirectly reflected. When the capacitor voltage transformer is in a residual voltage state, the primary side switch is turned off.
According to the embodiment, first differential values corresponding to at least one group of adjacent first sampling signals are obtained, and whether the capacitor voltage transformer is in a residual voltage state is determined according to each group of first differential values. The judgment process is simple, and a mode of acquiring the differential value of the sampling signal and performing related judgment can be adopted, so that the device has high response speed, the residual voltage state of the capacitor voltage transformer can be determined in time, and whether the primary side switch is disconnected or not can be determined in time.
Example two
The present embodiment further supplements the method for detecting the residual voltage state of the capacitor voltage transformer in the first embodiment.
Fig. 3 is a schematic flow chart of a method for detecting a residual voltage state of a capacitive voltage transformer according to the present embodiment. The method comprises the following steps:
This step is identical to step 201 and will not be described herein.
The predetermined time period may be greater than 1/4 of the system cycle, so that the first differential value has a zero-crossing value, which can ensure the accuracy of the determination result as much as possible. For example, the preset time period T may be T/4 < T ≦ T/2, where T is a system period of a system in which the capacitor voltage transformer is located. More specifically, the preset time period may be 0.3125 times the system period.
Alternatively, it may be determined whether the absolute values of the first difference values corresponding to each group are all smaller than a first preset threshold within a preset time period, and if the determination result is yes, it is then determined whether the absolute values of the first differential values are all smaller than a second preset threshold. In this way, it is first determined whether the first sampling signal is in a stable state, and if the determination result is no, it is not necessary to perform an operation of determining whether the absolute values of the first differential values are all smaller than the second preset threshold, which can reduce the workload of the apparatus. If the determination result is yes, the first sampling signal is in a stable state, and step 303 may be executed.
As shown in fig. 5, after the primary side switch of the capacitor voltage transformer is turned off, the differential value of the sampling signal is first sharply decreased and then is in a steady state. The integral value of the sampling signal is in a steady state after a long time after the primary side switch is turned off. Namely, the differential value of the sampling signal can quickly reflect whether the capacitor voltage transformer is in a residual voltage state or not. And when the differential value is in a steady state for a continuous period of time, for example, around 0V/s, it can be determined that the capacitor voltage transformer is in a residual voltage state.
The second difference in step 303 is the largest one minus the smallest one of the first differential values. In step 303, under the condition of considering the dc offset of the front-end sampling loop, the fault tolerance for the sampling error is increased, so that the final judgment result is more accurate.
If one of the results of the above determining steps is negative, which indicates that the capacitor voltage transformer is not in the residual voltage state, the step 301 may be executed again. Of course, other operations may be performed, and the details may be selected according to actual needs. For example, each time the first differential value of a group of adjacent first sampling signals is obtained, subsequent operations may be performed to realize real-time monitoring of the capacitor voltage transformer. Of course, step 301 may also be executed when the next monitoring period comes, which may be specifically defined according to actual needs.
And step 304, determining that the capacitor voltage transformer is in a residual voltage state.
In this embodiment, step 302 and step 303 may exist simultaneously or separately, for example, only step 302 or step 303 is executed. If only step 302 is executed, when the determination result in step 302 is yes, it can be determined that the capacitive voltage transformer is in a residual voltage state; if only step 303 is executed, when the determination result in step 303 is yes, it can be determined that the capacitor voltage transformer is in the residual voltage state.
According to the method for detecting the residual voltage state of the capacitive voltage transformer of the embodiment, after the first differential values of two adjacent first sampling signals are obtained, whether the first sampling signal is in the stable state is determined according to the absolute value of the difference value of the first differential values, and the stable state of the first sampling signal is further verified according to the absolute value of the first differential value of the first sampling signal, so that the residual voltage state of the capacitive voltage transformer can be timely and accurately determined.
EXAMPLE III
The present embodiment further supplements the method for detecting the residual voltage state of the capacitor voltage transformer in the foregoing embodiment.
Fig. 4 is a schematic flow chart of a method for indicating the residual voltage state of the capacitor voltage transformer according to the present embodiment. The method comprises the following steps:
In this step, the second differential values of two adjacent second sampling signals at the output end of the capacitor voltage transformer may be continuously obtained. Determining an absolute value of a third difference between the two second differential values, and determining whether the absolute value of the third difference is less than a fourth preset threshold. If the judgment result is yes, whether the absolute values of the two second differential values are both smaller than a fifth preset threshold value can be judged; if the absolute value of the third difference is greater than or equal to the fourth preset threshold, the second differential values of two adjacent second sampling signals of the next group may be obtained, and it is determined whether the absolute value of the third difference between the two second differential values is smaller than the fourth preset threshold. And under the condition that the absolute value of the third difference is judged to be smaller than a fourth preset threshold, the operation of judging whether the absolute values of the two second differential values are smaller than a fifth preset threshold is executed. If one or all of the two second differential values are greater than or equal to the fifth preset threshold, the next group of two adjacent second sampling signals may be obtained and it may be determined whether the absolute value of the difference between the corresponding second differential values is less than the fourth preset threshold.
In this step, if the determination result is negative, two adjacent second sampling signals may be continuously obtained.
This step 401 can be regarded as an initial condition for the capacitor voltage transformer to start to present residual charge, and after the initial condition is satisfied, the subsequent operation can be performed.
The fourth preset threshold of this embodiment may be greater than or equal to the first preset threshold, and the fifth preset threshold may be greater than or equal to the second preset threshold.
In the step, corresponding second integral values are obtained according to the second sampling signals, and whether absolute values of the second integral values are larger than a sixth preset threshold value is judged, so that the input end of the capacitor voltage transformer is determined to be input, and a switch of the capacitor voltage transformer is switched from a switched-on state to a switched-off state, and the capacitor voltage transformer is further verified to be in a residual voltage state.
And step 403, determining whether the absolute values of the two second integral values are in a decreasing trend along with time, if so, executing step 404, otherwise, returning to step 401.
The two adjacent integrated values meeting the conditions of 401 and 402 are determined to have a decreasing trend, which indicates that the amplitude of the integrated value of the second sampling signal is decreasing, and the capacitor voltage transformer is further verified to be in a residual voltage state. Specifically, if the absolute value of the second integrated value at a later time is smaller than the absolute value of the second integrated value at an earlier time, it can be determined that it is in a decreasing trend with time.
This step is identical to step 201 and will not be described herein.
This step 405 is identical to step 302 and will not be described further herein.
Step 406 is identical to step 303 and will not be described further herein.
It should be noted that, in this embodiment, step 402 and step 403 are not necessary, and step 406 is also not necessary, for example, only step 402 or step 403 is required. Of course, the order of step 403 and step 402 may be interchanged or performed simultaneously, for example, if the determination result of step 403 is no, step 402 may not be executed.
According to the method of the embodiment, the initial condition is firstly determined for detecting the residual voltage state of the capacitor voltage transformer, and when the condition is met, the subsequent steps are executed to determine whether the capacitor voltage transformer is in the residual voltage state, so that the process can be saved, and the burden of the device can be reduced.
Example four
The present embodiment exemplifies the detection of the residual voltage state of the capacitor voltage transformer in the foregoing embodiment.
As shown in fig. 5, the integrated value P curve and the differential value Q curve are illustrated schematically. In this embodiment, it is assumed that the first preset threshold is 0.3% Un, the second preset threshold is 1% Un, the third preset threshold is 1% Un, the fourth preset threshold is 0.4% Un, the fifth preset threshold is 1.2% Un, the sixth preset threshold is 3% Un, the seventh preset threshold is 0.4Un, and the preset time period is 0.3125T, where Un is a rated value of an integral value of the first sampling signal when the primary side normally operates, and T is a system period of a system in which the capacitor voltage transformer is located. It is to be noted that the physical meaning of the differential value Q is the rate of change of voltage with time, which is not in kV. In this embodiment, for the sake of comparison with the integral value P, the Q-curve represents a value obtained by converting the differential value into a corresponding voltage. That is, the Q curve reflects the correspondence relationship in which the differential value of the sampling signal is mapped onto the primary voltage. In order to make the relationship between the P-curve and the Q-curve clearer, the P-curve and the Q-curve are shown simultaneously in fig. 5.
In this embodiment, the integral value of the first sampling signal is Usec, i.e., a voltage value. As shown in table 1, the integral value and the differential value of the collected first sampling signal and the corresponding time point are shown. The corresponding Un in Table 1 is 110kV and T is 20 ms. Namely, the first preset threshold is 0.33kV, the second preset threshold is 1.1kV, the third preset threshold is 1.1kV, the fourth preset threshold is 0.44kV, the fifth preset threshold is 1.32kV, the sixth preset threshold is 3.3kV, the seventh preset threshold is 0.44kV, and the preset time period is 6.25 ms. Of course, the preset time period may be shorter, so that the determination time is shortened, and may be specifically set according to actual needs.
Firstly, whether the difference value between differential values corresponding to two adjacent sampling signals is smaller than a fourth preset threshold value of 0.44kV is judged. According to table 1, it can be seen that the first two adjacent sampled signals 1 and 2 have differential values of 27.50 and 2.800kV, respectively, and the absolute value of the difference between the two is 24.7kV, and 24.7kV is greater than 0.44kV, which does not satisfy the condition. Next, it is determined whether the difference between two adjacent sampling signals 2 and 3 of the second group is smaller than a fourth preset threshold. The second group of two adjacent sampled signals 1 and 2, whose corresponding differential values are 2.800kV and 1.100kV respectively, has an absolute value of the difference between the differential values of sampled signal 2 and sampled signal 3 of 1.7kV, and the second group of two adjacent sampled signals 2 and 3 do not satisfy this condition. Next, a third group of two adjacent sampling signals 3 and 4 is obtained, and the absolute value of the difference between the two sampling signals is 1.540kV, and the condition that the absolute value is less than 0.44kV is not satisfied. Next, a fourth set of two adjacent sampled signals 4 and 5 is obtained, the absolute value of the difference between them being 0.055kV, which is less than 0.44 kV. Then, the absolute values of the two differential values corresponding to the sampling signal 4 and the sampling signal 5 are judged to be smaller than a fifth preset threshold value 1.32 kV. Then, the integral values corresponding to the sampling signals 4 and 5 are acquired, the absolute values 68.200kV and 68.000kV of the two integral values are determined to be greater than the sixth preset threshold value 3.3kV, and then, whether the absolute values of the two integral values are in a decreasing trend with time is continuously determined, and likewise, the determination result is yes. At this point, the capacitive voltage transformer may begin to be in a residual voltage state, which may require further verification.
And acquiring differential values corresponding to two adjacent sampling signals 5 and 6 of a fifth group as-0.440 kV and-0.385 kV respectively, and judging that the absolute value of the difference value of the two differential values is 0.055kV and is smaller than a first preset threshold value 0.33kV, and the absolute values of the two differential values are smaller than a second preset threshold value 1.1 kV. Next, a sixth group of two adjacent sampling signals 6 and 7, a seventh group of two adjacent sampling signals 7 and 8, and an eighth group of two adjacent sampling signals 8 and 9 are obtained until the twenty-eighth group of two adjacent sampling signals, and the results of the judgment are the same as the results of the sampling signals 5 and 6. At which point the consecutive preset time periods have met the condition. Next, the maximum differential value of 0.440kV and the minimum differential value of 0.385kV are selected from the differential values corresponding to the sampling signals 5 to 29, and it is determined that the absolute value of the difference between the maximum differential value and the minimum differential value of 0.055kV is smaller than the third preset threshold value of 1.1 kV. At this time, it can be determined that the capacitor voltage transformer is in a residual voltage state, that is, the primary side switch is turned off, and the primary side voltage value should be 0V.
EXAMPLE five
The embodiment provides a device for detecting the residual voltage state of a capacitor voltage transformer. The device is used for executing the method for detecting the residual voltage state of the capacitor voltage transformer of the embodiment.
Fig. 6 is a schematic structural diagram of an apparatus for detecting a residual voltage state of a capacitive voltage transformer according to the present embodiment. The device for detecting the residual voltage state of the capacitive voltage transformer comprises an acquisition unit 601 and a determination unit 602. The acquiring unit 601 is configured to acquire first differential values of at least one group of adjacent first sampling signals at an output end of one capacitive voltage transformer; the determining unit 602 is configured to determine whether the capacitor voltage transformer is in a residual voltage state according to each group of the first differential values.
Optionally, the determining unit 602 is specifically configured to determine that the capacitive voltage transformer is in a residual voltage state if it is determined that the absolute values of the first differences between the two first differential values in each group are all smaller than a first preset threshold and the absolute values of the first differential values are all smaller than a second preset threshold in consecutive preset time periods.
The preset time period T in this embodiment may be T/4 < T ≦ T/2, where T is a system period of a system in which the capacitor voltage transformer is located.
According to the embodiment, first differential values of at least one group of adjacent first sampling signals are obtained, and whether the capacitor voltage transformer is in a residual voltage state is determined according to the first differential values of each group. The judgment process is simple, and a mode of acquiring the differential value of the sampling signal and performing related judgment can be adopted, so that the device has high response speed, the residual voltage state of the capacitor voltage transformer can be determined in time, and whether the primary side switch is disconnected or not can be determined in time.
EXAMPLE six
The present embodiment further provides a supplementary description of the apparatus for detecting a residual voltage state of a capacitive voltage transformer in the sixth embodiment.
Fig. 7 is a schematic structural diagram of an apparatus for detecting a residual voltage state of a capacitive voltage transformer according to the present embodiment. In the apparatus, the determining unit 602 includes a first judging subunit 701, a second judging subunit 702, and a determining subunit 703.
The first determining subunit 701 is connected to the obtaining unit 601, where the first determining subunit 701 is configured to determine, in consecutive preset time periods, whether absolute values of first differences between two first differential values in each group are all smaller than a first preset threshold, and whether absolute values of the first differential values are all smaller than a second preset threshold, and if the determination result is yes, trigger the second determining subunit 702; the second determining subunit 702 is connected to the first determining subunit 701, where the second determining subunit 702 is configured to determine whether a second difference between a largest one and a smallest one of the first differential values in a preset time period is smaller than a third preset threshold, and if the second difference is smaller than the third preset threshold, trigger a determining subunit 703; the determining subunit 703 is connected to the second determining subunit 702, and the determining subunit 703 is configured to determine that the capacitive voltage transformer is in a residual voltage state.
The determining subunit 703 is configured to determine that the capacitor voltage transformer is in the residual voltage state, that is, if the determining subunit 703 is triggered, that is, the capacitor voltage transformer is in the residual voltage state, the determining subunit 703 may notify an operator in a manner of sending a signal, for example, displaying a text on a computer.
The working method of each subunit of this embodiment is the same as that of the previous embodiment, and is not described herein again.
According to the device of the embodiment, after the first differential values of two adjacent first sampling signals are acquired, whether the first sampling signals are in a stable state is determined according to the absolute value of the difference value of the first differential values, and the stable state of the first sampling signals is further verified according to the absolute value of the first differential values of the first sampling signals, so that the residual voltage state of the capacitor voltage transformer can be timely and accurately determined.
EXAMPLE seven
The present embodiment is directed to the apparatus for detecting a residual voltage state of a capacitive voltage transformer of the previous embodiment.
Fig. 8 is a schematic structural diagram of an apparatus for detecting a residual voltage state of a capacitive voltage transformer according to the present embodiment. The apparatus includes a judging unit 801 in addition to the units in the fifth embodiment and the sixth embodiment. The determining unit 801 is configured to determine whether an absolute value of a third difference between second differential values of two adjacent second sampling signals at the output end of the capacitive voltage transformer is smaller than a fourth preset threshold, and whether the absolute values of the two second differential values are both smaller than a fifth preset threshold, and if the determination result is yes, trigger the obtaining unit 601.
Optionally, after determining that the absolute value of the third difference between the second differential values of two adjacent second sampling signals at the output end of the capacitive voltage transformer is smaller than a fourth preset threshold, and before triggering the obtaining unit 601, the determining unit 801 is further configured to:
it is determined whether the absolute values of the second integrated values of the two second sampling signals are both greater than a sixth preset threshold, and if the determination result is yes, the acquiring unit 601 is triggered.
Fig. 8 shows a specific structure of the determining unit 602, but the determining unit 602 may also adopt other structures, which are not described herein again.
The working method of each subunit of this embodiment is the same as that of the previous embodiment, and is not described herein again.
According to the embodiment, the initial condition is firstly determined for detecting the residual voltage state of the capacitor voltage transformer, and when the condition is met, the subsequent steps are executed to determine whether the capacitor voltage transformer is in the residual voltage state, so that the process can be saved, and the burden of the device can be reduced.
Example eight
The embodiment provides another device for detecting the residual voltage state of the capacitor voltage transformer. As shown in fig. 9, the apparatus 900 for detecting a residual voltage state of a capacitive voltage transformer comprises at least one communication interface 901, at least one memory 902, and at least one processor 903.
The communication interface 901 is used for communicating with a capacitor voltage transformer; the memory 901 is configured to store first differential values of at least one group of adjacent first sampling signals at the output end of the capacitor voltage transformer; a processor 903 is connected to the memory 902, and the processor 903 is used in the method for detecting the residual voltage state of the capacitor voltage transformer in any of the embodiments. The memory 902 may be provided in the processor 903 or may be provided separately.
According to the embodiment, first differential values of at least one group of adjacent first sampling signals are obtained, and whether the capacitor voltage transformer is in a residual voltage state is determined according to the first differential values of each group. The judgment process is simple, and a mode of acquiring the differential value of the sampling signal and performing related judgment can be adopted, so that the device has high response speed, the residual voltage state of the capacitor voltage transformer can be determined in time, and whether the primary side switch is disconnected or not can be determined in time.
The invention also provides a device for detecting the residual voltage state of the capacitor voltage transformer, which comprises at least one memory and at least one processor. Wherein the memory is to store instructions. The processor is configured to execute the method for detecting the residual voltage state of the capacitive voltage transformer described in any of the foregoing embodiments according to instructions stored in the memory.
Embodiments of the present invention also provide a readable storage medium. The readable storage medium has stored therein machine readable instructions which, when executed by a machine, the machine performs the method of detecting the residual voltage status of a capacitive voltage transformer described in any of the foregoing embodiments.
The readable storage medium has stored thereon machine readable instructions which, when executed by a processor, cause the processor to perform any of the methods previously described. In particular, a system or apparatus may be provided which is provided with a readable storage medium on which software program code implementing the functionality of any of the embodiments described above is stored and which causes a computer or processor of the system or apparatus to read and execute machine-readable instructions stored in the readable storage medium.
In this case, the program code itself read from the readable storage medium can realize the functions of any of the above-described embodiments, and thus the machine-readable code and the readable storage medium storing the machine-readable code constitute a part of the present invention.
Examples of the readable storage medium include floppy disks, hard disks, magneto-optical disks, optical disks (e.g., CD-ROMs, CD-R, CD-RWs, DVD-ROMs, DVD-RAMs, DVD-RWs, DVD + RWs), magnetic tapes, nonvolatile memory cards, and ROMs. Alternatively, the program code may be downloaded from a server computer or from the cloud via a communications network.
It will be understood by those skilled in the art that various changes and modifications may be made in the above-disclosed embodiments without departing from the spirit of the invention. Accordingly, the scope of the invention should be determined from the following claims.
It should be noted that not all steps and units in the above flows and system structure diagrams are necessary, and some steps or units may be omitted according to actual needs. The execution order of the steps is not fixed and can be adjusted as required. The apparatus structures described in the above embodiments may be physical structures or logical structures, that is, some units may be implemented by the same physical entity, or some units may be implemented by a plurality of physical entities, or some units may be implemented by some components in a plurality of independent devices.
In the above embodiments, the hardware unit may be implemented mechanically or electrically. For example, a hardware unit or processor may comprise permanently dedicated circuitry or logic (such as a dedicated processor, FPGA or ASIC) to perform the corresponding operations. The hardware units or processors may also include programmable logic or circuitry (e.g., a general purpose processor or other programmable processor) that may be temporarily configured by software to perform the corresponding operations. The specific implementation (mechanical, or dedicated permanent, or temporarily set) may be determined based on cost and time considerations.
While the invention has been shown and described in detail in the drawings and in the preferred embodiments, it is not intended to limit the invention to the embodiments disclosed, and it will be apparent to those skilled in the art that various combinations of the code auditing means in the various embodiments described above may be used to obtain further embodiments of the invention, which are also within the scope of the invention.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (15)
1. The method for detecting the residual voltage state of the capacitor voltage transformer is characterized by comprising the following steps:
acquiring first differential values of at least one group of adjacent first sampling signals at the output end of one capacitor voltage transformer;
determining whether the capacitor voltage transformer is in a residual voltage state or not according to each group of the first differential values;
determining whether the capacitor voltage transformer is in a residual voltage state according to each group of the first differential values, wherein the determining comprises the following steps:
and in a continuous preset time period, if the absolute value of a first difference value between two first differential values in each group is judged to be smaller than a first preset threshold value and the absolute value of each first differential value is judged to be smaller than a second preset threshold value, determining that the capacitor voltage transformer is in a residual voltage state.
2. The method of claim 1, further comprising, after determining that the absolute values of the first differences between the two first differential values in each group are less than a first preset threshold and each of the first differential values is less than a second preset threshold, and before determining that the capacitive voltage transformer is in the residual voltage state:
judging whether a second difference value between the maximum one and the minimum one of the first differential values is smaller than a third preset threshold value within the preset time period;
and if so, executing the operation of determining that the capacitor voltage transformer is in the residual voltage state.
3. The method according to claim 1 or 2, further comprising, before obtaining the first differential values of at least one group of adjacent first sampled signals at the output of one capacitive voltage transformer:
judging whether the absolute value of a third difference value between second differential values of two adjacent second sampling signals at the output end of the capacitor voltage transformer is smaller than a fourth preset threshold value or not, and whether the absolute values of the two second differential values are both smaller than a fifth preset threshold value or not;
and if the judgment results are yes, performing operation of acquiring first differential values of at least one group of adjacent first sampling signals at the output end of one capacitor voltage transformer.
4. The method of claim 3, further comprising, after determining that an absolute value of a third difference between second differential values of two adjacent second sampled signals at the output of the capacitive voltage transformer is smaller than a fourth preset threshold, and before performing the operation of obtaining first differential values of at least one group of adjacent first sampled signals at the output of the capacitive voltage transformer:
and determining whether the absolute values of the second integral values corresponding to the two second sampling signals are both greater than a sixth preset threshold, and if so, executing the operation of acquiring at least one group of adjacent first sampling signals at the output end of the capacitor voltage transformer.
5. The method according to claim 4, wherein after determining that the absolute values of the second integrated values corresponding to the two second sampling signals are greater than a sixth preset threshold, and before performing the operation of acquiring at least one group of adjacent first sampling signals at the output end of the capacitive voltage transformer, the method further comprises:
determining whether the absolute values of the two second integrated values are in a decreasing trend with time;
and if the determination result is yes, performing operation of acquiring at least one group of adjacent first sampling signals of the output end of the capacitor voltage transformer.
6. The method according to claim 1, wherein the preset time period T is T/4 < T ≦ T/2, where T is a system period of a system in which the capacitive voltage transformer is located.
7. Device for detecting residual voltage state of capacitor voltage transformer, comprising:
an acquisition unit which acquires first differential values of at least one group of adjacent first sampling signals at the output end of a capacitor voltage transformer;
a determining unit, for determining whether the capacitor voltage transformer is in residual voltage state according to each group of the first differential values;
the determining unit is specifically configured to:
and in a continuous preset time period, if the absolute value of a first difference value between two first differential values in each group is judged to be smaller than a first preset threshold value and the absolute value of each first differential value is judged to be smaller than a second preset threshold value, determining that the capacitor voltage transformer is in a residual voltage state.
8. The apparatus of claim 7, wherein the determining unit comprises:
a first judging subunit, configured to, within consecutive preset time periods, judge whether absolute values of first differences between two first differential values in each group are all smaller than a first preset threshold, and whether absolute values of the first differential values are all smaller than a second preset threshold, and if the judgment result is yes, trigger a second judging subunit;
the second judging subunit is configured to judge whether a second difference between a largest one and a smallest one of the first differential values in the preset time period is smaller than a third preset threshold, and if the second difference is smaller than the third preset threshold, trigger a determining subunit;
and the determining subunit is used for determining the operation that the capacitor voltage transformer is in a residual voltage state.
9. The apparatus of claim 7 or 8, further comprising:
and the judging unit is used for judging whether the absolute value of a third difference value between second differential values of two adjacent second sampling signals at the output end of the capacitor voltage transformer is smaller than a fourth preset threshold value or not, judging whether the absolute values of the two second differential values are smaller than a fifth preset threshold value or not, and triggering the acquiring unit if the judgment result is yes.
10. The apparatus of claim 9, wherein after determining that the absolute value of the third difference between the second differential values of two adjacent second sampling signals at the output end of the capacitive voltage transformer is smaller than a fourth preset threshold, and before triggering the obtaining unit, the determining unit is further configured to:
and determining whether the absolute values of the second integral values corresponding to the two second sampling signals are both greater than a sixth preset threshold, and if so, triggering the acquisition unit.
11. The apparatus of claim 10, wherein after determining that the absolute values of the second integrated values corresponding to the two second sampling signals are both greater than a sixth preset threshold, and before performing the operation of acquiring at least one group of adjacent first sampling signals at the output end of the capacitive voltage transformer, the determining unit is further configured to:
determining whether the absolute values of the two second integrated values are in a decreasing trend with time;
and if the determination result is yes, performing operation of acquiring at least one group of adjacent first sampling signals of the output end of the capacitor voltage transformer.
12. The device according to claim 7, wherein the preset time period T is T/4 < T ≦ T/2, where T is a system period of a system in which the capacitive voltage transformer is located.
13. Device for detecting residual voltage state of capacitor voltage transformer, comprising:
at least one communication interface for communicating with the capacitive voltage transformer;
at least one memory for storing first differential values of at least one set of adjacent first sampled signals at the output of the capacitive voltage transformer;
at least one processor connected to the memory, the processor configured to perform the method of detecting a residual voltage state of a capacitive voltage transformer according to any one of claims 1-6.
14. The device for detecting the residual voltage state of the capacitor voltage transformer is characterized by comprising at least one memory, a voltage detection unit and a voltage detection unit, wherein the at least one memory is used for storing instructions;
at least one processor configured to execute the method of detecting a residual voltage condition of a capacitive voltage transformer of any one of claims 1-6 in accordance with instructions stored by the memory.
15. Readable storage medium, in which machine readable instructions are stored, which when executed by a machine, perform a method of detecting a residual voltage state of a capacitive voltage transformer according to any one of claims 1 to 6.
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