Method and device for determining current based on optical current transformer

Abstract

The invention provides a method and a device for determining current based on an optical current transformer. The method comprises the following steps: acquiring each first emergent light intensity sampling value generated by a first optical current transformer according to a preset sampling period; acquiring each second emergent light intensity sampling value generated by the second optical current transformer according to the preset sampling period; identifying whether each first emergent light intensity sampling value exceeds the first light intensity measurement range or not; determining a first final real-time current value of the target equipment at the same sampling moment according to the first emergent light intensity sampling value and the second emergent light intensity sampling value at the same sampling moment under the condition that the first emergent light intensity sampling value is located in the first light intensity measurement range; and generating a current waveform of the target equipment according to the first final real-time current value, and executing relay protection operation according to the current waveform.

Description

Technical Field

[0001] The present invention relates to the field of power systems, and particularly to a method and device for determining current based on an optical current transformer. Background Art

[0002] For an optical current transformer (OCT), its working principle mainly uses the Faraday magneto-optical effect to calculate the current of the device to be measured. That is, in a magneto-optical material, an externally applied magnetic field can cause the linearly polarized plane propagating in the medium along the magnetic field direction to deflect accordingly. The deflection angle of the incident light is related to the intensity of the magnetic field (through the magnitude of the current), the length of the interaction between light and the magnetic field in the transparent material, and the properties of the material. Therefore, by measuring the deflected angle, the magnitude of the primary side current can be calculated.

[0003] Therefore, how to accurately determine the magnitude of the primary side current has become an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the present invention proposes a method for determining current based on an optical current transformer. A target device corresponds to a first optical current transformer and a second optical current transformer at the same time. The target device uses alternating current. Both the first optical current transformer and the second optical current transformer are used to determine the real-time current value of the target device. The real-time current of the target device is proportional to the intensity of the outgoing light of the first optical current transformer, and the real-time current of the target device is proportional to the intensity of the outgoing light of the second optical current transformer. The first optical current transformer corresponds to a first light intensity measurement range, and the second optical current transformer corresponds to a second light intensity measurement range. The second light intensity measurement range is larger than the first light intensity measurement range.

[0005] The method includes:

[0006] Obtain each first outgoing light intensity sampling value generated by the first optical current transformer according to a preset sampling period;

[0007] Obtain each second outgoing light intensity sampling value generated by the second optical current transformer according to the preset sampling period;

[0008] Identify whether each of the first outgoing light intensity sampling values exceeds the first light intensity measurement range;

[0009] When the first outgoing light intensity sampling value is within the first light intensity measurement range, determine the first final real-time current value of the target device at the same sampling moment according to the first outgoing light intensity sampling value and the second outgoing light intensity sampling value at the same sampling moment;

[0010] Generate the current waveform of the target device based on the first final real-time current value, and perform a relay protection operation according to the current waveform.

[0011] According to the method described above, optionally, it further includes:

[0012] If the recognition result is that the second emitted light intensity sampling value exceeds the second light intensity measurement range, then use the last second emitted light intensity sampling value that does not exceed the second light intensity measurement range as the first final light intensity of the target device within a first time period, and determine the second final real-time current value of the target device within the first time period according to the first final light intensity, where the second emitted light intensity sampling values all exceed the second light intensity measurement range within the first time period;

[0013] Generate the current waveform of the target device according to the second final real-time current value.

[0014] According to the method described above, optionally, it further includes:

[0015] If it is recognized that the first emitted light intensity sampling value exceeds the first light intensity measurement range, then in the case where it is determined that the second emitted light intensity sampling value is within the second light intensity measurement range, determine the fourth final real-time current value of the target device according to the second emitted light intensity sampling value.

[0016] According to the method described above, optionally, determining the first final real-time current of the target device at the same sampling moment according to the first emitted light intensity sampling value and the second emitted light intensity sampling value at the same sampling moment includes:

[0017] Determine the first current value according to the first emitted light intensity sampling value at the same sampling moment;

[0018] Determine the second current value according to the second emitted light intensity sampling value at the same sampling moment;

[0019] Determine the first final real-time current of the target device at the same sampling moment according to the following formula: First final real-time current = First current value * Preset weight value + Second current value * (1 - Preset weight value).

[0020] According to the method described above, optionally, the preset weight value q satisfies 0.7 ≤ q ≤ 0.9.

[0021] According to the method described above, optionally, the first optical current transformer corresponds to a first maximum light intensity measurement value and a first minimum light intensity measurement value, the second optical current transformer corresponds to a second maximum light intensity measurement value and a second minimum light intensity measurement value, the second maximum measurement value is greater than the first maximum measurement value, and the second minimum measurement value is less than the first minimum measurement value;

[0022] The

[0023] The

[0024] The

[0025] The

[0026]

[0027]

[0028]

[0029]

[0030] Wherein, is 45°, I1 is the intensity of the incident light of the first optical current transformer, I2 is the intensity of the incident light of the second optical current transformer, γ1 is the deflection angle of the incident light of the first optical current transformer, and γ2 is the deflection angle of the incident light of the first optical current transformer.

[0031] A device for determining current based on an optical current transformer. A target device corresponds to a first optical current transformer and a second optical current transformer at the same time. The target device uses alternating current. Both the first optical current transformer and the second optical current transformer are used to determine the real-time current value of the target device. The real-time current of the target device is proportional to the light intensity of the outgoing light of the first optical current transformer, and the real-time current of the target device is proportional to the light intensity of the outgoing light of the second optical current transformer. The first optical current transformer corresponds to a first light intensity measurement range, and the second optical current transformer corresponds to a second light intensity measurement range. The second light intensity measurement range is greater than the first light intensity measurement range;

[0032] The device includes:

[0033] A sampling unit for obtaining each first outgoing light intensity sampling value generated by the first optical current transformer according to a preset sampling period, and obtaining each second outgoing light intensity sampling value generated by the second optical current transformer according to the preset sampling period;

[0034] An identification unit for identifying whether each of the first emitted light intensity sampling values exceeds the first light intensity measurement range. If the identification result is negative, a first determination unit is triggered;

[0035] The first determination unit is configured to determine the first final real-time current value of the target device at the same sampling moment according to the first emitted light intensity sampling value and the second emitted light intensity sampling value at the same sampling moment;

[0036] A generation unit for generating a current waveform of the target device according to the first final real-time current value;

[0037] An operation unit for performing a relay protection operation according to the current waveform.

[0038] According to the device described above, optionally, it further includes:

[0039] A setting unit for, if the identification result is that the second emitted light intensity sampling value exceeds the second light intensity measurement range, using the last second emitted light intensity sampling value that does not exceed the second light intensity measurement range as the first final light intensity of the target device within a first time period;

[0040] A second determination unit for determining the second final real-time current value of the target device within the first time period according to the first final light intensity, where the second emitted light intensity sampling values all exceed the second light intensity measurement range within the first time period;

[0041] The generation unit is configured to generate a current waveform of the target device according to the second final real-time current value.

[0042] According to the device described above, optionally, it further includes:

[0043] A third determination unit for, if it is identified that the first emitted light intensity sampling value exceeds the first light intensity measurement range, and when it is determined that the second emitted light intensity sampling value is within the second light intensity measurement range, determining the fourth final real-time current value of the target device according to the second emitted light intensity sampling value.

[0044] According to the device described above, optionally, the first determination unit is specifically configured to:

[0045] Determine the first current value according to the first emitted light intensity sampling value at the same sampling moment;

[0046] Determine the second current value according to the second emitted light intensity sampling value at the same sampling moment;

[0047] Determine the first final real-time current of the target device at the same sampling moment according to the following formula: First final real-time current = First current value * Preset weight value + Second current value * (1 - Preset weight value).

[0048] According to the device described above, optionally, the first optical current transformer corresponds to a first maximum light intensity measurement value and a first minimum light intensity measurement value, the second optical current transformer corresponds to a second maximum light intensity measurement value and a second minimum light intensity measurement value, the second maximum measurement value is greater than the first maximum measurement value, and the second minimum measurement value is less than the first minimum measurement value;

[0049] The

[0050] The

[0051] The

[0052] The

[0053]

[0054]

[0055]

[0056]

[0057] Wherein, is 45°, I1 is the intensity of the incident light of the first optical current transformer, I2 is the intensity of the incident light of the second optical current transformer, γ1 is the deflection angle of the incident light of the first optical current transformer, and γ2 is the deflection angle of the incident light of the first optical current transformer.

[0058] The present invention also provides a device for determining current based on an optical current transformer, including:

[0059] At least one memory for storing instructions;

[0060] At least one processor for executing the method for determining current based on an optical current transformer according to any one of the above based on the instructions stored in the memory.

[0061] The present invention further provides a readable storage medium, in which machine-readable instructions are stored, and when the machine-readable instructions are executed by a machine, the machine executes the method for determining current based on an optical current transformer according to any one of the above.

[0062] As can be seen from the above solution, the present invention determines the real-time current of the target device through two optical current transformers, which can not only expand the measurement range of the optical current transformer, but also improve the measurement accuracy when the current is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The following will describe in detail the preferred embodiments of the present invention with reference to the accompanying drawings, so that those of ordinary skill in the art can more clearly understand the above and other features and advantages of the present invention. In the drawings:

[0064] Figure 1 is a schematic diagram of a current waveform determined based on an optical current transformer in the prior art.

[0065] Figure 2 is a schematic flowchart of a method for determining current based on an optical current transformer according to an embodiment of the present invention.

[0066] Figure 3A is a schematic diagram of a current waveform corresponding to the method for determining current based on an optical current transformer according to an embodiment of the present invention.

[0067] Figure 3B is a schematic diagram of a current waveform corresponding to the method for determining current based on an optical current transformer according to another embodiment of the present invention.

[0068] Figure 4A is a schematic diagram of the current waveform in each state corresponding to the method for determining current based on an optical current transformer according to an embodiment of the present invention.

[0069] Figure 4B is a schematic diagram of a current waveform corresponding to an optical current transformer according to an embodiment of the present invention.

[0070] Figure 5 is a schematic structural diagram of a device for determining current based on an optical current transformer according to an embodiment of the present invention.

[0071] Figure 6A is a schematic structural diagram of a device for determining current based on an optical current transformer according to another embodiment of the present invention.

[0072] Figure 6B is a schematic structural diagram of a device for determining current based on an optical current transformer according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0073] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe the present invention in detail with reference to embodiments. In this patent application, nouns and pronouns related to people are not limited to specific genders.

[0074] The inventor found that when the deflection angle of the incident light of the optical current transformer exceeds a certain angle, the measured current value of the optical current transformer will deviate.

[0075] Specifically, according to the formula obtained from Malus' law: I = I0·cos 2 α, where I is the light intensity of the outgoing light, I0 represents the light intensity of the incident light, and α represents the deflection angle of the incident light. Generally, the deflection angle of the incident light of the optical current transformer is within 45°.

[0076] According to the Faraday effect, α(t) = B(t)·V·d;

[0077] According to Ampere's circuital law,

[0078] Based on the above two formulas,

[0079] Furthermore, the following formula is obtained:

[0080]

[0081] where i(t) represents the current of the device at time t, α(t) represents the deflection angle of the incident light at time t, μ r represents the relative permeability of the optical current transformer, μ0 represents the vacuum permeability of the optical current transformer, V represents the Verdet constant of the optical current transformer, r represents the radius of the magnetic field closed loop, and d represents the length of the light passing through the medium.

[0082] It can be seen from the above formula that the larger the deflection angle α(t), the larger the real-time current of the device. However, due to the monotonicity of the cosine function, if the deflection angle of the incident light ranges from 45° to negative degrees and then increases from negative degrees to 45 degrees, the graph of the real-time current of the device obtained by the optical current transformer is as Figure 1 shown, where the abscissa is time in milliseconds (ms) and the ordinate is current in kA. From Figure 1 it can be seen that for the waveform of the real-time current in section E, it is distorted. The waveform of the real-time current obtained based on the optical current transformer will be sent to the relay protection device, and the relay protection device is very likely to malfunction due to the distorted waveform at this point.

[0083] For the above reasons, the present invention provides a method for determining current based on an optical current transformer, which is used to determine the real-time current of a target device. The target device can be any device that needs to measure current, such as a switch cabinet, and the measured current is the primary side current. The target device of the present invention corresponds to a first optical current transformer and a second optical current transformer at the same time. Both the first optical current transformer and the second optical current transformer are used to determine the real-time current value of the target device. The real-time current of the target device is proportional to the light intensity of the outgoing light of the first optical current transformer, and the real-time current of the target device is proportional to the light intensity of the outgoing light of the second optical current transformer. The first optical current transformer corresponds to a first light intensity measurement range, and the second optical current transformer corresponds to a second light intensity measurement range. The second light intensity measurement range is greater than the first light intensity measurement range. Here, the second light intensity measurement range being greater than the first light intensity measurement range means that the wavelength of the incident wave of the first optical current transformer is less than the wavelength of the incident wave of the second optical current transformer. Here, the first light intensity measurement range means less than or equal to the first maximum light intensity measurement value and greater than or equal to the first minimum light intensity measurement value, and the second light intensity measurement range means less than or equal to the second maximum light intensity measurement value and greater than or equal to the second minimum light intensity measurement value. The accuracy of the second optical current transformer is lower than that of the first optical current transformer. Especially when the real-time current of the target device is small, the error of the real-time current value obtained based on the second optical current transformer will be large. Therefore, it is necessary to combine the first optical current transformer to determine the real-time current value.

[0084] The present invention takes two optical current transformers as an example to process the real-time current of the measured target device, which can avoid mis-triggering the operation of the relay protection device. It should be noted that in actual applications, there may not be only two optical current transformers. For example, there may be three, four or even more current transformers.

[0085] Embodiment 1

[0086] This embodiment provides a method for determining current based on an optical current transformer. The execution subject of this method is a device for determining current based on an optical current transformer. This device can be integrated into a relay protection device or can be set separately, which will not be elaborated here. For the first optical current transformer and the second optical current transformer, the wavelengths of their light sources can be quite different. Such a combination is beneficial to measuring a larger range of real-time current on the premise of ensuring accuracy.

[0087] As Figure 2 shown, it is a schematic flow chart of the method for determining current based on an optical current transformer according to this embodiment. This method includes:

[0088] Step 101: Obtain each first emitted light intensity sampling value generated by the first optical current transformer according to a preset sampling period, and obtain each second emitted light intensity sampling value generated by the second optical current transformer according to the preset sampling period.

[0089] The wavelength of the light of the light source corresponding to the first optical current transformer is less than the wavelength of the wave of the light source corresponding to the second optical current transformer. The first optical current transformer senses the real-time current of the target device and generates emitted light. The device for determining the current samples according to the preset sampling period, and the obtained light intensity of the emitted light is the first emitted light intensity sampling value. That is, it is necessary to monitor the light intensity of the emitted light of the first optical current transformer in real time.

[0090] The second optical current transformer senses the real-time current of the target device and generates emitted light. The device for determining the current samples the second optical current transformer according to the preset sampling period, and the obtained light intensity of the emitted light is the second emitted light intensity sampling value. That is, it is necessary to monitor the light intensity of the emitted light of the second optical current transformer in real time.

[0091] In this embodiment, the device for determining the current based on the optical current transformer samples the first optical current transformer and the second optical current transformer simultaneously according to the same preset sampling period.

[0092] Step 102: Identify whether each of the first emitted light intensity sampling values exceeds the first light intensity measurement range. If all the identification results are yes, then execute Step 103.

[0093] As an exemplary illustration, it is necessary to monitor the first emitted light intensity sampling value and the second emitted light intensity sampling value at the same moment in real time. It can be determined whether the first emitted light intensity sampling value is within the first light intensity measurement range. If not, it means that it exceeds the first light intensity measurement range. It can also be determined whether the second emitted light intensity sampling value is within the second light intensity measurement range. Since each emitted light intensity sampling value is continuously collected, it is necessary to continuously monitor whether each first emitted light intensity sampling value is within the first light intensity measurement range, and continuously monitor whether each second emitted light intensity sampling value is within the second light intensity measurement range. Of course, in the case where the second light intensity measurement range is greater than the first light intensity measurement range, it is also possible to determine whether the second emitted light intensity sampling value is within the second light intensity measurement range after identifying that the first emitted light intensity sampling value exceeds the first light intensity measurement range. Specifically, it can be selected according to actual needs and will not be elaborated here.

[0094] The first light intensity measurement range of this embodiment can be determined according to the characteristics of the first optical current transformer, and the second light intensity measurement range can also be determined according to the characteristics of the second optical current transformer. It should be noted that the first light intensity measurement range is not the maximum or minimum light intensity that the first optical current transformer can measure, but the inflection point where the real-time current obtained based on the outgoing light intensity of the first optical current transformer begins to deviate from the true current. For example Figure 1 the inflection point F in

[0095] That is, the real-time current obtained based on the outgoing light intensity within the first light intensity measurement range is consistent with the true current, and the real-time current obtained based on the outgoing light intensity outside the first light intensity measurement range is inconsistent with the true current. Similarly, the second light intensity measurement range is not the maximum or minimum light intensity that the second optical current transformer can measure, but the inflection point where the real-time current obtained based on the outgoing light intensity of the second optical current transformer is inconsistent with the true current. That is, the real-time current obtained based on the outgoing light intensity within the second light intensity measurement range is consistent with the true current, and the real-time current obtained based on the outgoing light intensity outside the second light intensity measurement range is inconsistent with the true current.

[0096] Step 103, when the first outgoing light intensity sampling value is within the first light intensity measurement range, determine the first final real-time current of the target device at the same sampling moment according to the first outgoing light intensity sampling value and the second outgoing light intensity sampling value at the same sampling moment.

[0097] Specifically, a first current value can be determined according to the first outgoing light intensity sampling value, a second current value can be determined according to the second outgoing light intensity sampling value at the same moment, and the first final real-time current at the target sampling moment can be determined according to the weight of the first current value and the weight of the second current value.

[0098] Of course, other methods can also be used to determine the first final real-time current at the target sampling moment according to the first outgoing light intensity sampling value and the second outgoing light intensity sampling value. For example, a new outgoing light intensity sampling value is obtained by weighting the first outgoing light intensity sampling value and the second outgoing light intensity sampling value, and a new incident light intensity sampling value is also obtained by weighting the two incident light intensity sampling values. The first final real-time current at the target sampling moment is obtained according to the new incident light intensity sampling value and the new outgoing light intensity sampling value.

[0099] Since the accuracy of the first optical current transformer is higher than that of the second optical current transformer, therefore, comprehensively, when far from point F, the proportion of the sampled value of the first outgoing light intensity can be set higher, and when close to point F, the proportion of the sampled value of the first outgoing light intensity can be set lower. In this way, jumps at point F can be avoided, which may cause the waveform to be non-smooth, and further, misoperations caused by waveform jumps can be avoided.

[0100] As a specific example, this step includes:

[0101] Determine a first current value according to the sampled value of the first outgoing light intensity at the same sampling moment;

[0102] Determine a second current value according to the sampled value of the second outgoing light intensity at the same sampling moment;

[0103] Determine the first final real-time current of the target device at the same sampling moment according to the following formula: First final real-time current = First current value * Preset weight value + Second current value * (1 - Preset weight value).

[0104] Specifically, how to determine the current value of the target device according to the sampled value of the outgoing light intensity belongs to the prior art and will not be elaborated here. The preset weight value here can be set according to actual needs. For example, the preset weight value q satisfies 0.7 ≤ q ≤ 0.9. Adjusting the weight of the first current value to be higher can make the accuracy of the first final real-time current higher.

[0105] In addition, the same sampling moment here means that the sampling moments of the sampled values of the first outgoing light intensity corresponding to the first current value and the second current value used when determining the first final real-time current are the same. The situation where the first outgoing light intensity sampling value is within the first light intensity measurement range will last for a period of time, and there are multiple first final real-time current values during this period, and corresponding current waveforms can be formed.

[0106] Step 104, generate a current waveform of the target device according to the first final real-time current, and perform a relay protection operation according to this current waveform.

[0107] Specifically, the corresponding waveform can be formed according to all the first final real-time current values. That is, when the outgoing light intensity is within the first light intensity measurement range, the method of this embodiment is used to obtain the first final real-time current value in the above situation and generate the corresponding current waveform. For details, see Figure 3A Current waveform S2. The relay protection device will perform corresponding relay protection operations according to this current waveform. Specifically, how to perform corresponding protection operations according to the current waveform belongs to the prior art and will not be elaborated here.

[0108] Optionally, the target device may also correspond to multiple optical current transformers such as the third optical current transformer, the fourth optical current transformer, etc. The corresponding light intensity measurement ranges are all different. For two adjacent optical current transformers with different light intensity measurement ranges, the method of this embodiment can be used to obtain the final real-time current in the corresponding situation. For example, if there is a third optical current transformer and the third light intensity measurement range corresponding to the third optical current transformer is greater than the second light intensity measurement range, when it is recognized that the first outgoing light intensity sampling value exceeds the first light intensity measurement range and the second outgoing light intensity sampling value is within the second light intensity measurement range, based on the second outgoing light intensity sampling value at the same moment and the third outgoing light intensity sampling value of the third optical current transformer, the real-time current value during this time period is determined, and a waveform is generated accordingly. This can avoid jumps at the inflection point and improve the accuracy of the third optical current transformer. By analogy, it will not be elaborated here.

[0109] According to this embodiment, by using two optical current transformers to determine the real-time current of the target device, while expanding the measurement range of the optical current transformer, the measurement accuracy can be improved when the current is small.

[0110] Embodiment 2

[0111] This embodiment further supplements and explains the method for determining current based on an optical current transformer in Embodiment 1. In this embodiment, it mainly describes that after exceeding the first optical measurement range and the second optical measurement range, the real-time current waveforms obtained based on the first optical current transformer and the real-time current waveforms obtained based on the second optical current transformer are processed to avoid other misoperations caused by their distortion.

[0112] In this embodiment, if the recognition result is that the second outgoing light intensity sampling value exceeds the second light intensity measurement range, then the last second outgoing light intensity sampling value that does not exceed the second light intensity measurement range is used as the first final light intensity of the target device in the first time period, and the second final real-time current of the target device in the first time period is determined according to the first final light intensity, where the second outgoing light intensity sampling values all exceed the second light intensity measurement range in the first time period;

[0113] A current waveform of the target device is generated according to the second final real-time current.

[0114] For example, as Figure 3A and Figure 3B shown, the abscissa is time, with the unit of second (s), and the ordinate is current. Specifically, a column of numbers close to the ordinate axis represents the current with the unit of kA. Figure 3A S2 in Figure 3BS4 in it refers to the current waveform when the first sampled emitted light intensity value exceeds the first light intensity measurement range and the second sampled emitted light intensity value has never exceeded the second light intensity measurement range. As Figure 3A shown, the part between time A and time B represents the first time period when the sampled second emitted light intensity value exceeds the second light intensity measurement range. Among them, the second sampled emitted light intensity value at the sampling moment before time A is used as the last second sampled emitted light intensity value that does not exceed the second light intensity measurement range, and the real-time current of the target device determined according to this second sampled emitted light intensity value is the second final real-time current value. During the first time period between time A and time B, the current waveform is generated with this second final real-time current value, that is, the current waveform within the first time period after being processed is as Figure 3A shown by the AB segment in S2 in it. Time A is the starting point of the first time period, and time B is the ending point of the first time period. In this way, the current waveform obtained according to this second real-time current will not cause misoperation of the relay protection device.

[0115] Similarly, if the recognition result is that the first sampled emitted light intensity value exceeds the first light intensity measurement range, then the last first sampled emitted light intensity value that does not exceed the first light intensity measurement range is used as the second final light intensity of the target device within the second time period, and the third final real-time current of the target device within the second time period is determined according to this second final light intensity;

[0116] The current waveform of the target device is generated according to the third final real-time current.

[0117] S1 in Figure 3, Figure 3B S3 in Figure 4B and Figure 4B are the real-time current waveforms obtained based on the first optical current transformer. Among them, the current waveforms in the second time period between time C and time D all adopt the third final real-time current. In this way, misoperation of the relay protection device will not be caused due to this current waveform. S1 in Figure 3 and Figure 4B S5 in

[0118] The real-time current waveforms obtained based on the first optical current transformer refer to the current waveforms obtained by correcting the real-time current corresponding to the exceeded part when the first sampled emitted light intensity value exceeds the first light intensity measurement range. This correction means using the last first sampled emitted light intensity value that does not exceed the first light intensity measurement range as the second final light intensity of the target device within the second time period, and determining the third final real-time current of the target device within the second time period according to this second final light intensity.

[0118] Optionally, if it is recognized that the first sampled emitted light intensity value is within the first light intensity measurement range, the current waveform of the target device is generated according to the first sampled emitted light intensity value and the second sampled emitted light intensity value, and the relay protection operation is performed according to this current waveform.

[0119] That is Figure 3A the current waveform S2 consists of three parts. When the emitted light intensity of the first optical current transformer is within the first light intensity measurement range, it is regarded as state 0. When the emitted light intensity of the first current transformer is greater than or equal to the first maximum light intensity measurement value and the emitted light intensity of the second current transformer is less than or equal to the second maximum light intensity measurement value, it is regarded as state 1. When the emitted light intensity of the first current transformer is less than or equal to the first minimum light intensity measurement value and the emitted light intensity of the second current transformer is greater than or equal to the second minimum light intensity measurement value, it is regarded as state -1. When the emitted light intensity of the second current transformer is greater than the second maximum light intensity measurement value, it is regarded as state 2. When the emitted light intensity of the second current transformer is less than the second minimum light intensity measurement value, it is regarded as state -2, as Figure 3A represented by the column of numbers on the left side of the vertical axis in. Among them, when the first emitted light intensity sampling value is within the first light intensity measurement range, the part corresponding to the current waveform S2 is determined based on the first emitted light intensity sampling value and the second emitted light intensity sampling value; when the first emitted light intensity sampling value exceeds the first light intensity measurement range and the second emitted light intensity sampling value is within the second light intensity measurement range, the part corresponding to the current waveform S2 is obtained based on the second emitted light intensity sampling value. For example, the fourth final real-time current value of the target device during this period is determined according to the second emitted light intensity sampling value, and the waveform is determined accordingly; when the second emitted light intensity sampling value exceeds the second light intensity measurement range, the part corresponding to the current waveform S2 is obtained based on the second final real-time current value, and the final current waveform is Figure 3A S2 in, and the current protection device performs relay protection operations according to this current waveform.

[0120] Figure 3B the current waveform S4 in consists of two parts Figure 3B without being in state 2 or state -2. For Figure 3BThe current waveform S4. When the sampling value of the first emitted light intensity is within the first light intensity measurement range, the part corresponding to the current waveform S4 is determined based on the sampling value of the first emitted light intensity and the sampling value of the second emitted light intensity; in the case where the sampling value of the first emitted light intensity exceeds the first light intensity measurement range and the sampling value of the second emitted light intensity is within the second light intensity measurement range, the part corresponding to the current waveform S4 is obtained from the sampling value of the second emitted light intensity. For example, the fourth final real-time current value of the target device during this period is determined according to the sampling value of the second emitted light intensity, and the waveform is accordingly determined. Regarding the case where the emitted light intensity of the first optical current transformer is within the first light intensity measurement range as state 0, regarding the case where the emitted light intensity of the first current transformer is greater than or equal to the first maximum light intensity measurement value and the emitted light intensity of the second current transformer is less than or equal to the second maximum light intensity measurement value as state 1, and regarding the case where the emitted light intensity of the first current transformer is less than or equal to the first minimum light intensity measurement value and the emitted light intensity of the second current transformer is greater than or equal to the second minimum light intensity measurement value as state -1, as Figure 3B shown by the column of numbers far from the ordinate.

[0121] In this way, for the case where further operations need to be performed separately using the real-time current waveform based on the first optical current transformer, or for the case where further operations need to be performed based on the real-time current waveform of the second optical current transformer, it is possible to avoid misoperations caused by the original distorted waveform.

[0122] Embodiment III

[0123] This embodiment further supplements and explains the method for determining current based on an optical current transformer in the foregoing embodiment.

[0124] In this embodiment, the first light intensity measurement range corresponds to a first maximum light intensity measurement value and a first minimum light intensity measurement value, and the second light intensity measurement range corresponds to a second maximum light intensity measurement value and a second minimum light intensity measurement value, where the second maximum measurement value is greater than the first maximum measurement value, and the second minimum measurement value is less than the first minimum measurement value.

[0125] In this embodiment,

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133] Among them, is 45°, I1 is the intensity of the incident light of the first optical current transformer, I2 is the intensity of the incident light of the second optical current transformer, γ1 is the deflection angle of the incident light of the first optical current transformer, and γ2 is the deflection angle of the incident light of the first optical current transformer.

[0134] The preset factor here can be set according to the actual situation. For example, it can be set according to the characteristics of the optical current transformer. The preset factor is 0 < preset factor < 1. For example, it is 0.9. Of course, it can also be other values, which will not be elaborated here.

[0135] As an example, the first optical current transformer and the second optical current transformer are simultaneously used to measure the primary side current of a target device. The real-time output light intensity of the first optical current transformer and the second optical current transformer is input to the relay protection device, and the relay protection device will also know in advance the incident light intensity of each of the first optical current transformer and the second optical current transformer. More specifically, the relay protection device includes two circuit boards. The first circuit board is used to perform protection analysis on the input current waveform to trigger corresponding protection actions. The second circuit board is used to collect the light intensity information sent by the first optical current transformer and the second optical current transformer, and generate a corresponding current waveform and input it into the first circuit board. Other devices can also obtain the current waveform generated by the second circuit board.

[0136] In this embodiment, when the output light intensity of the first optical current transformer is within the first light intensity measurement range, it is regarded as state 0. When the output light intensity of the first current transformer is greater than or equal to the first maximum light intensity measurement value and the output light intensity of the second current transformer is less than or equal to the second maximum light intensity measurement value, it is regarded as state 1. When the output light intensity of the first current transformer is less than or equal to the first minimum light intensity measurement value and the output light intensity of the second current transformer is greater than or equal to the second minimum light intensity measurement value, it is regarded as state -1. When the output light intensity of the second current transformer is greater than the second maximum light intensity measurement value, it is regarded as state 2. When the output light intensity of the second current transformer is less than the second minimum light intensity measurement value, it is regarded as state -2, as Figure 3A and Figure 3B shown. As Figure 4AAs shown, it is a schematic diagram of the flow of each state according to this embodiment. That is, from state 0 to state 1, then from state 1 to state 2, then from state 2 back to state 1, and then from state 1 back to state 0. Similarly, from state 0 to state -1, then from state -1 to state -2, then from state -2 back to state -1, and then from state -1 back to state 0.

[0137] The relay protection device continues to sample the emitted light intensity of the first optical current transformer and the emitted light intensity of the second optical current transformer at the same sampling period, and obtains the first emitted light intensity sampling value and the second emitted light intensity sampling value at the same moment.

[0138] Figure 4B It is a schematic diagram of the current waveform when the first emitted light intensity sampling value exceeds the first light intensity measurement range, where S5 is the schematic diagram of the current waveform obtained solely based on the first optical current transformer. Specifically, if it is determined that the current is in state 0 according to the first emitted light intensity sampling value, the current waveform S5 obtained based on the first emitted light intensity sampling value is as Figure 4B the segment from M1 to N1 in the figure. If it is recognized that the first emitted light intensity sampling value exceeds the first light intensity measurement range, then the first final real-time current value of the target device at the target sampling moment is determined based on the last first emitted light intensity sampling value that does not exceed the first light intensity measurement range, and the segment from N1 to P1 of the current waveform S5 in Figure 4B the figure is obtained; if it is recognized that the first emitted light intensity sampling value returns to within the first light intensity measurement range, that is, returns to state 0, then the current waveform S5 obtained based on the first emitted light intensity sampling value is as Figure 4B the segment from P1 to Q1 in the figure. And so on.

[0139] If the second emitted light intensity sampling value exceeds the second light intensity measurement range, for the current waveform obtained solely based on the second optical current transformer, its shape is similar to Figure 4B that. In addition, as shown by the current waveform S2 in Figure 3A the figure, it is a schematic diagram of the current waveform output from the second circuit board to the first circuit board, which shows the current waveform between state 0, state 1, and state 2. This current waveform S2 is used by the first circuit board to perform subsequent relay protection operations according to this current waveform.

[0140] Embodiment 4

[0141] This embodiment provides a device for determining current based on an optical current transformer. This device can be integrated into a relay protection device, can also be set separately, or can be regarded as the relay protection device itself, which will not be elaborated here. For the first optical current transformer and the second optical current transformer, the wavelengths of their light sources can differ significantly. Such a combination is beneficial for measuring a larger range of real-time current while ensuring accuracy.

[0142] As Figure 5 shown, it is a schematic structural diagram of a device for determining current based on an optical current transformer according to this embodiment. The device for determining current based on an optical current transformer includes a sampling unit 501, an identification unit 502, a first determination unit 503, a generation unit 504, and an operation unit 505.

[0143] Among them, the sampling unit 501 is configured to obtain each first emitted light intensity sampling value generated by the first optical current transformer according to a preset sampling period, and obtain each second emitted light intensity sampling value generated by the second optical current transformer according to the preset sampling period; the identification unit 502 is configured to identify whether each first emitted light intensity sampling value exceeds the first light intensity measurement range. If the identification result is negative, a first determination unit 503 is triggered; the first determination unit 503 is configured to determine a first final real-time current value of the target device at the same sampling moment according to the first emitted light intensity sampling value and the second emitted light intensity sampling value at the same sampling moment; the generation unit 504 is configured to generate a current waveform of the target device according to the first final real-time current value; the operation unit 505 is configured to perform a relay protection operation according to the current waveform.

[0144] Optionally, the first determination unit 503 is specifically configured to:

[0145] Determine a first current value according to the first emitted light intensity sampling value at the same sampling moment;

[0146] Determine a second current value according to the second emitted light intensity sampling value at the same sampling moment;

[0147] Determine the first final real-time current of the target device at the same sampling moment according to the following formula: First final real-time current = First current value * preset weight value + Second current value * (1 - preset weight value).

[0148] Optionally, the preset weight value q satisfies 0.7 ≤ q ≤ 0.9.

[0149] Optionally, the first optical current transformer corresponds to a first maximum light intensity measurement value and a first minimum light intensity measurement value, the second optical current transformer corresponds to a second maximum light intensity measurement value and a second minimum light intensity measurement value, the second maximum measurement value is greater than the first maximum measurement value, and the second minimum measurement value is less than the first minimum measurement value;

[0150]

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158] Among them, is 45°, I1 is the intensity of the incident light of the first optical current transformer, I2 is the intensity of the incident light of the second optical current transformer, γ1 is the deflection angle of the incident light of the first optical current transformer, and γ2 is the deflection angle of the incident light of the first optical current transformer.

[0159] The working methods of the various units in this embodiment are the same as those in the foregoing embodiment, and will not be elaborated here.

[0160] According to this embodiment, when the light intensity of the outgoing light caused by the real-time current of the target device is beyond the first light intensity measurement range of the first optical current transformer and within the second light intensity measurement range of the second optical current transformer, by using two optical current transformers, the real-time current of the target device in the above situation is obtained by integrating the first outgoing light intensity sampling value and the second outgoing light intensity sampling value. This real-time current is closer to the real current of the target device. The relay protection operation is performed according to the current waveform generated based on this real-time current, which can avoid misoperation.

[0161] Embodiment 5

[0162] This embodiment further supplements and explains the device for determining current based on an optical current transformer in Embodiment 4.

[0163] As Figure 6A shown, it is a schematic structural diagram of the device for determining current based on an optical current transformer according to this embodiment. The device for determining current based on an optical current transformer in this embodiment, in addition to the sampling unit 501, the identification unit 502, the first determination unit 503, the generation unit 504, and the operation unit 505 included in the foregoing embodiment, further includes a setting unit 601 and a second determination unit 602.

[0164] Among them, the setting unit 601 is configured to use the last second emitted light intensity sampling value that does not exceed the second light intensity measurement range as the first final light intensity of the target device within a first time period if the recognition result is that the second emitted light intensity sampling value exceeds the second light intensity measurement range; the second determination unit 602 is configured to determine the second final real-time current value of the target device within the first time period according to the first final light intensity, and the second emitted light intensity sampling values all exceed the second light intensity measurement range within the first time period; correspondingly, the generation unit 504 is configured to generate the current waveform of the target device according to the second final real-time current value.

[0165] Optionally, as Figure 6B shown, the device for determining current based on an optical current transformer further includes a third determination unit 603. The third determination unit 603 is configured to determine the fourth final real-time current value of the target device according to the second emitted light intensity sampling value if it is recognized that the first emitted light intensity sampling value exceeds the first light intensity measurement range and the second emitted light intensity sampling value is within the second light intensity measurement range. The operation of recognizing that the first emitted light intensity sampling value exceeds the first light intensity measurement range can be specifically completed by the recognition unit 502 and notified to the third determination unit 603, or the third determination unit 603 actively obtains it from the recognition unit 502. Correspondingly, the generation unit is configured to generate the current waveform of the target device according to the fourth final real-time current value.

[0166] The working methods of the units in this embodiment are the same as those in the foregoing embodiments and will not be elaborated here.

[0167] In this way, the current waveform obtained according to the second final real-time current will not cause misoperation of the relay protection device.

[0168] The present invention also provides a device for determining current based on an optical current transformer, including at least one memory and at least one processor. Among them, the memory is used to store instructions. The processor is configured to execute the method for determining current based on an optical current transformer described in any of the foregoing embodiments according to the instructions stored in the memory. The device for determining current based on an optical current transformer can be the relay protection device itself.

[0169] An embodiment of the present invention also provides a readable storage medium. Machine-readable instructions are stored in the readable storage medium. When the machine-readable instructions are executed by a machine, the machine executes the method for determining current based on an optical current transformer described in any of the foregoing embodiments.

[0170] Machine-readable instructions are stored on the readable medium, and when executed by a processor, the machine-readable instructions cause the processor to execute any of the foregoing methods. Specifically, a system or device equipped with a readable storage medium may be provided, on which software program code for implementing the functions of any one of the above embodiments is stored, and the computer or processor of the system or device is caused to read and execute the machine-readable instructions stored in the readable storage medium.

[0171] In this case, the program code read from the readable medium itself can implement the functions of any one of the above embodiments, so the machine-readable code and the readable storage medium storing the machine-readable code constitute a part of the present invention.

[0172] Examples of the readable storage medium include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tapes, non-volatile memory cards, and ROMs. Optionally, the program code may be downloaded from a server computer or a cloud via a communication network.

[0173] Those skilled in the art should understand that various modifications and variations can be made to the above-disclosed embodiments without departing from the essence of the invention. Therefore, the protection scope of the present invention should be defined by the appended claims.

[0174] It should be noted that not all steps and units in the above-mentioned processes and system structure diagrams are necessary, and some steps or units can be ignored according to actual needs. The execution order of the steps is not fixed and can be adjusted according to needs. The device structures described in the above embodiments can 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 multiple physical entities respectively, or some components in multiple independent devices may be jointly implemented.

[0175] In the above embodiments, the hardware units can be implemented mechanically or electrically. For example, a hardware unit or a processor may include permanent dedicated circuits or logics (such as dedicated processors, FPGAs or ASICs) to complete corresponding operations. The hardware unit or the processor may also include programmable logics or circuits (such as general-purpose processors or other programmable processors), which can be temporarily set by software to complete corresponding operations. The specific implementation method (mechanical method, or dedicated permanent circuit, or temporarily set circuit) can be determined based on cost and time considerations.

[0176] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. Method for determining current based on optical current transformers. A target device corresponds to a first optical current transformer and a second optical current transformer at the same time. The target device uses alternating current. Both the first optical current transformer and the second optical current transformer are used to determine the real-time current value of the target device. The real-time current of the target device is proportional to the intensity of the outgoing light of the first optical current transformer, and the real-time current of the target device is proportional to the intensity of the outgoing light of the second optical current transformer. The first optical current transformer corresponds to a first light intensity measurement range, and the second optical current transformer corresponds to a second light intensity measurement range. The second light intensity measurement range is larger than the first light intensity measurement range; The method includes: Obtaining each first outgoing light intensity sampling value generated by the first optical current transformer according to a preset sampling period; Obtaining each second outgoing light intensity sampling value generated by the second optical current transformer according to the preset sampling period; Identifying whether each of the first outgoing light intensity sampling values exceeds the first light intensity measurement range; When the first outgoing light intensity sampling value is within the first light intensity measurement range, determining a first final real-time current value of the target device at the same sampling moment according to the first outgoing light intensity sampling value and the second outgoing light intensity sampling value at the same sampling moment; Generating a current waveform of the target device according to the first final real-time current value, and performing a relay protection operation according to the current waveform.

2. The method according to claim 1, wherein It further includes: If the identification result is that the second outgoing light intensity sampling value exceeds the second light intensity measurement range, then taking the last second outgoing light intensity sampling value that does not exceed the second light intensity measurement range as the first final light intensity of the target device within a first time period, and determining a second final real-time current value of the target device within the first time period according to the first final light intensity. The second outgoing light intensity sampling values all exceed the second light intensity measurement range within the first time period; Generating a current waveform of the target device according to the second final real-time current value.

3. The method according to claim 1, wherein It further includes: If it is identified that the first outgoing light intensity sampling value exceeds the first light intensity measurement range, then when it is determined that the second outgoing light intensity sampling value is within the second light intensity measurement range, determining a fourth final real-time current value of the target device according to the second outgoing light intensity sampling value.

4. The method according to claim 1, wherein Determining the first final real-time current of the target device at the same sampling moment according to the first outgoing light intensity sampling value and the second outgoing light intensity sampling value at the same sampling moment includes: Determining a first current value according to the first outgoing light intensity sampling value at the same sampling moment; Determining a second current value according to the second outgoing light intensity sampling value at the same sampling moment; Determining the first final real-time current of the target device at the same sampling moment according to the following formula: First final real-time current = First current value * preset weight value + Second current value * (1 - preset weight value).

5. The method according to claim 4, wherein The preset weight value q satisfies 0.7 ≤ q ≤ 0.

9.

6. The method according to any one of claims 1-5, characterized in that The first optical current transformer corresponds to a first maximum light intensity measurement value and a first minimum light intensity measurement value. The second optical current transformer corresponds to a second maximum light intensity measurement value and a second minimum light intensity measurement value. The second maximum measurement value is greater than the first maximum measurement value, and the second minimum measurement value is less than the first minimum measurement value; The said The said The said The Wherein, is 45°, I1 is the intensity of the incident light of the first optical current transformer, I2 is the intensity of the incident light of the second optical current transformer, γ1 is the deflection angle of the incident light of the first optical current transformer, and γ2 is the deflection angle of the incident light of the first optical current transformer.

7. A device for determining current based on an optical current transformer. A target device corresponds to a first optical current transformer and a second optical current transformer at the same time. The target device uses alternating current. Both the first optical current transformer and the second optical current transformer are used to determine the real-time current value of the target device. The real-time current of the target device is proportional to the emitted light intensity of the first optical current transformer, and the real-time current of the target device is proportional to the emitted light intensity of the second optical current transformer. The first optical current transformer corresponds to a first light intensity measurement range, and the second optical current transformer corresponds to a second light intensity measurement range. The second light intensity measurement range is greater than the first light intensity measurement range; The device includes: A sampling unit for obtaining each first emitted light intensity sampling value generated by the first optical current transformer according to a preset sampling period, and obtaining each second emitted light intensity sampling value generated by the second optical current transformer according to the preset sampling period; An identification unit for identifying whether each of the first emitted light intensity sampling values exceeds the first light intensity measurement range. If the identification result is no, a first determination unit is triggered; The first determination unit for determining a first final real-time current value of the target device at the same sampling moment according to the first emitted light intensity sampling value and the second emitted light intensity sampling value at the same sampling moment; A generation unit for generating a current waveform of the target device according to the first final real-time current value; An operation unit for performing a relay protection operation according to the current waveform.

8. The device according to claim 7, characterized in that, It further includes: A setting unit for, if the identification result is that the second emitted light intensity sampling value exceeds the second light intensity measurement range, taking the last second emitted light intensity sampling value that does not exceed the second light intensity measurement range as the first final light intensity of the target device within a first time period; A second determination unit for determining a second final real-time current value of the target device within the first time period according to the first final light intensity, and the second emitted light intensity sampling values all exceed the second light intensity measurement range within the first time period; The generation unit is used to generate a current waveform of the target device according to the second final real-time current value.

9. The device according to claim 7, wherein It further includes: A third determination unit for, if it is identified that the first emitted light intensity sampling value exceeds the first light intensity measurement range, and when it is determined that the second emitted light intensity sampling value is within the second light intensity measurement range, determining a fourth final real-time current value of the target device according to the second emitted light intensity sampling value.

10. The device according to claim 7, characterized in that The first determination unit is specifically used for: Determine the first current value according to the first emitted light intensity sampling value at the same sampling moment; Determine the second current value according to the second emitted light intensity sampling value at the same sampling moment; Determine the first final real-time current of the target device at the same sampling moment according to the following formula: First final real-time current = First current value * preset weight value + Second current value * (1 - preset weight value).

11. The device according to any one of claims 7 to 10, characterized in that, The first optical current transformer corresponds to a first maximum light intensity measurement value and a first minimum light intensity measurement value, the second optical current transformer corresponds to a second maximum light intensity measurement value and a second minimum light intensity measurement value, the second maximum measurement value is greater than the first maximum measurement value, and the second minimum measurement value is less than the first minimum measurement value; The The above-mentioned The said The said Among them, is 45°, I1 is the intensity of the incident light of the first optical current transformer, I2 is the intensity of the incident light of the second optical current transformer, γ1 is the deflection angle of the incident light of the first optical current transformer, and γ2 is the deflection angle of the incident light of the first optical current transformer.

12. Device for determining current based on an optical current transformer, characterized in that, Including: At least one memory for storing instructions; At least one processor for executing the method for determining current based on an optical current transformer according to any one of claims 1-6 according to the instructions stored in the memory.

13. A readable storage medium, characterized in that, Machine-readable instructions are stored in the readable storage medium, and when the machine-readable instructions are executed by a machine, the machine executes the method for determining current based on an optical current transformer according to any one of claims 1-6.

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