Self-adaptive safety device of voltage transformer and operation method of self-adaptive safety device

Abstract

The invention provides a self-adaptive safety device of a voltage transformer and an operation method thereof, the self-adaptive safety device comprises a first fuse, and the first fuse and the voltage transformer are connected in series on a voltage measurement loop of a bus; each compensation branch comprises a first switch and a compensation resistor, and the first switch and the compensation resistor are connected in series between the first end and the second end of the first fuse; the detection module is used for collecting the first voltage of the first fuse; and the control module is used for controlling the on-off of the plurality of first switches according to the first voltage of the first fuse, so that the first voltage is not greater than the rated voltage of the voltage transformer in a preset proportion. According to the self-adaptive safety device of the voltage transformer and the operation method of the self-adaptive safety device, safe operation of the voltage transformer is guaranteed through voltage reduction and current limiting, meanwhile, the measurement precision requirement of the voltage transformer is met, and the self-adaptive safety device can adapt to the low-frequency replacement scene of the first fuse.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of voltage transformer protection, in particular to an adaptive fuse device of a voltage transformer and a running method thereof. BACKGROUND

[0002] In a power system, series resonance often occurs, which leads to fuse blowing or slow melting of a voltage transformer (PT) fuse, and further leads to abnormal voltage measurement loop, which affects the normal work of relay protection, metering and other automatic devices, and the replacement of the PT fuse needs to be performed as soon as possible.

[0003] However, at present, most power stations or substations do not have replacement conditions due to the implementation of unattended operation in specific scenarios, and often need to take more safety measures, or need to consume a long time due to a long distance, so that the PT fuse cannot be replaced in time, and the slow melting or blowing of the PT fuse causes unnecessary losses to the system operation, such as measurement errors or safety risks caused by protection loss. SUMMARY

[0004] The present disclosure aims to at least solve one of the technical problems in the related art to some extent.

[0005] To this end, the purpose of the present disclosure is to provide an adaptive fuse device of a voltage transformer and a running method thereof.

[0006] To achieve the above purpose, the first aspect of the present disclosure provides an adaptive fuse device of a voltage transformer, comprising: a first fuse, the first fuse and the voltage transformer being connected in series on a voltage measurement loop of a bus; a plurality of compensation branches, the plurality of compensation branches being connected in parallel at both ends of the first fuse respectively, and the compensation branch comprising: a first switch and a compensation resistor, the first switch and the compensation resistor being connected in series between a first end and a second end of the first fuse; a detection module, a detection end of the detection module being connected with the first fuse, and the detection module being configured to collect a first voltage of the first fuse; a control module, a signal input end of the control module being connected with a signal output end of the detection module, and a signal output end of the control module being connected with a signal input end of the first switch, and the control module being configured to control the on-off of the plurality of first switches according to the first voltage of the first fuse, so that the first voltage is not greater than a preset proportion of a rated voltage of the voltage transformer.

[0007] Optionally, the compensation branch further comprises a second fuse, the second fuse being connected in series with the first switch and the compensation resistor respectively, and a first end of the first switch and a first end of the first fuse being connected, a first end of the compensation resistor and a second end of the first switch being connected, a second end of the second fuse and a second end of the compensation resistor being connected, and a second end of the second fuse and a second end of the first fuse being connected.

[0008] Optionally, the compensation branch further comprises a second switch, the second switch being connected in series between a second end of the second fuse and a second end of the first fuse, and a first end of the second switch and the second end of the second fuse being connected, and a second end of the second switch and the second end of the first fuse being connected; wherein the signal output end of the control module is connected with the signal input end of the first switch and the signal input end of the second switch respectively, and the control module is configured to control the on-off of the plurality of first switches and the plurality of second switches according to the first voltage of the first fuse, so that the first voltage is not greater than a preset proportion of the rated voltage of the voltage transformer.

[0009] Optionally, the compensation branch comprises a relay, a coil of the relay being connected in series on a control loop of the control module, and a first normally open contact of the relay being connected in series between the first end of the compensation resistor and the first end of the first fuse as the first switch, and a second normally open contact of the relay being connected in series between the second end of the second fuse and the second end of the first fuse as the second switch; wherein the control module is configured to control the on-off of the control loop according to the first voltage of the first fuse, so as to control the on-off of the first normally open contact and the second normally open contact in the relay.

[0010] Optionally, the detection module comprises an isolation transformer, a primary side of the isolation transformer being connected in parallel on the first fuse; a low-pass filter, an alternating current input end of the low-pass filter being connected with a secondary side of the isolation transformer; a voltage conversion unit, an alternating current input end of the voltage conversion unit being connected with an alternating current output end of the low-pass filter, and a direct current output end of the voltage conversion unit being connected with a signal input end of the control module.

[0011] The second aspect of the present disclosure provides a method for operating an adaptive fuse device of a voltage transformer as provided in the first aspect of the present disclosure, comprising: obtaining a first voltage of a first fuse in the device, a rated voltage of the voltage transformer, and a measurement accuracy; calculating a second voltage based on the rated voltage of the voltage transformer and according to a proportion corresponding to the measurement accuracy; comparing the first voltage and the second voltage, and when the first voltage is greater than the second voltage, issuing an alarm and calculating a total impedance of a voltage measurement loop in the device; calculating an allowed maximum resistance of the first fuse based on the total impedance of the voltage measurement loop and according to the proportion corresponding to the measurement accuracy; and controlling on-off of a plurality of first switches in the device according to the allowed maximum resistance of the first fuse, so that a total resistance of a compensation resistance corresponding to the first switch that is turned on and the first fuse is less than the allowed maximum resistance of the first fuse.

[0012] Optionally, the method further comprises: when the first voltage is an open circuit voltage, taking a second fuse corresponding to the first switch that is turned on in the device as a new first fuse, and controlling on-off of the remaining first switches in the device, so that a total resistance of a compensation resistance corresponding to the first switch that is turned on in the remaining first switches and a compensation resistance corresponding to the new first fuse is less than the allowed maximum resistance of the first fuse.

[0013] Optionally, the method further comprises: controlling on-off of a plurality of first switches in the device, so that a total resistance of a compensation resistance corresponding to the first switch that is turned on and the first fuse is half of the allowed maximum resistance of the first fuse.

[0014] Optionally, the method further comprises: calculating a reactance of the voltage transformer based on the rated voltage of the voltage transformer, a three-phase load of the voltage transformer, and a direct current resistance of the voltage transformer; and calculating the total impedance of the voltage measurement loop based on the reactance and the direct current resistance of the voltage transformer.

[0015] Optionally, the method further comprises: calculating the reactance of the voltage transformer based on a first formula, wherein the first formula is: wherein x is the reactance of the voltage transformer, U is the rated voltage of the voltage transformer, S is the three-phase load of the voltage transformer, and r is the direct current resistance of the voltage transformer; calculating the total impedance of the voltage measurement loop based on a second formula, wherein the second formula is: wherein Z is the total impedance of the voltage measurement loop; and calculating the allowed maximum resistance of the first fuse based on a third formula, wherein the third formula is: K is the proportion corresponding to the measurement accuracy, and R is the total resistance of the compensation resistance corresponding to the first switch in conduction and the first fuse.

[0016] The technical solutions provided by the present disclosure can include the following beneficial effects:

[0017] When the first fuse slowly melts and develops, the first voltage of the first fuse rises, and the control module controls the on-off of the plurality of first switches according to the first voltage, so that the first fuse can be integrated into the compensation resistance corresponding to the first switch in conduction, so that the first voltage of the first fuse is not greater than the voltage of the voltage transformer rated voltage of the preset proportion, thereby meeting the measurement accuracy requirement of the voltage transformer while ensuring the safe operation of the voltage transformer through voltage reduction and current limiting. Among them, based on the automatic operation of the compensation branch, the replacement time of the first fuse is effectively delayed, which can adapt to the low-frequency replacement scene of the first fuse; in addition, the control module directly obtains the voltage drop across the first fuse by using the detection module, which has higher accuracy and sensitivity.

[0018] Additional aspects and advantages of the present disclosure will be partially given in the following description, partially will become apparent from the following description, or will be understood by practicing the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and / or additional aspects and advantages of the present disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 is a circuit schematic diagram of the adaptive fuse device of the voltage transformer according to an embodiment of the present disclosure;

[0021] Figure 2 is a circuit schematic diagram of the compensation branch in the adaptive fuse device of the voltage transformer according to an embodiment of the present disclosure;

[0022] Figure 3 is a circuit schematic diagram of the relay coil in the adaptive fuse device of the voltage transformer according to an embodiment of the present disclosure;

[0023] Figure 4 is a circuit schematic diagram of the detection module in the adaptive fuse device of the voltage transformer according to an embodiment of the present disclosure;

[0024] Figure 5 is an equivalent circuit diagram according to an embodiment of the present disclosure;

[0025] Figure 6 is a resistance and voltage drop curve diagram according to an embodiment of the present disclosure;

[0026] As shown in the figure: 1, first fuse;

[0027] 2, detection module, 21, isolation transformer, 22, low-pass filter, 23, voltage conversion unit;

[0028] 3, control module;

[0029] 4, compensation branch, 41, first switch, 42, compensation resistor, 43, second fuse, 44, second switch, 45, coil;

[0030] 5, voltage transformer. DETAILED DESCRIPTION

[0031] The embodiments of the present disclosure are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present disclosure, and cannot be understood as a limitation of the present disclosure. On the contrary, the embodiments of the present disclosure include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.

[0032] As shown in Figure 1 and Figure 2 The adaptive fuse device of the voltage transformer 5 is provided by the embodiments of the present disclosure, which comprises a first fuse 1, a plurality of compensation branches 4, a detection module 2 and a control module 3. The first fuse 1 and the voltage transformer 5 are connected in series on the voltage measurement loop of the bus. The plurality of compensation branches 4 are connected in parallel at both ends of the first fuse 1, respectively. The compensation branch 4 comprises a first switch 41 and a compensation resistor 42, which are connected in series between the first end and the second end of the first fuse 1. The detection end of the detection module 2 is connected to the first fuse 1, and the detection module 2 is used to collect the first voltage of the first fuse 1. The signal input end of the control module 3 is connected to the signal output end of the detection module 2, and the signal output end of the control module 3 is connected to the signal input end of the first switch 41. The control module 3 is used to control the on-off of the plurality of first switches 41 according to the first voltage of the first fuse 1, so that the first voltage is not greater than the voltage transformer 5 rated voltage of the preset proportion.

[0033] It can be understood that, since the first fuse 1 and the voltage transformer 5 are connected in series on the voltage measurement loop of the bus, the voltage transformer 5 can realize voltage measurement of the voltage measurement loop and the voltage measurement of the corresponding bus of the voltage measurement loop, and also realizes circuit protection by using the first fuse 1. In addition, since the plurality of compensation branches 4 are connected in parallel at both ends of the first fuse 1, and the first switch 41 and the compensation resistor 42 in the compensation branch 4 are connected in series between the first end and the second end of the first fuse 1, when the first switch 41 is turned on, the compensation resistor 42 corresponding to the first switch 41 can be put into operation to the first fuse 1. At the same time, since the detection end of the detection module 2 is connected with the first fuse 1, the signal input end of the control module 3 is connected with the signal output end of the detection module 2, and the signal output end of the control module 3 is connected with the signal input end of the first switch 41, the control module 3 can obtain the first voltage of the first fuse 1 by using the detection module 2, and can control the on-off of the first switch 41.

[0034] Based on this, when the first fuse 1 slowly melts and develops, the first voltage of the first fuse 1 rises, and the control module 3 controls the on-off of the plurality of first switches 41 according to the first voltage, so that the first fuse 1 can be connected to the compensation resistor 42 corresponding to the turned-on first switch 41, so that the first voltage of the first fuse 1 is not greater than the voltage transformer 5 rated voltage of the preset proportion, thereby meeting the measurement accuracy requirement of the voltage transformer 5 while ensuring the safe operation of the voltage transformer 5 by reducing the voltage and limiting the current.

[0035] Among them, based on the automatic operation of the compensation branch 4, the replacement time of the first fuse 1 is effectively delayed, which can adapt to the low-frequency replacement scene of the first fuse 1.

[0036] In addition, the control module 3 directly obtains the voltage drop between the two ends of the first fuse 1 by using the detection module 2, which has higher accuracy and sensitivity.

[0037] It should be noted that the first fuse 1 and the voltage transformer 5 (PT) are used to be connected in series on the voltage measurement loop of the bus (A phase, B phase, C phase) to realize accurate and safe measurement of the bus voltage. The specific type of the first fuse 1 and the voltage transformer 5 can be set according to actual needs, which is not limited.

[0038] The compensation branch 4 has a plurality of, which constitutes an adaptive resistance matrix. For example, the plurality of compensation branches 4 are sequentially put into operation in the voltage measurement loop according to the rising change of the first voltage, wherein at most two compensation branches 4 are simultaneously put into operation.

[0039] The compensation resistor 42 is used for voltage reduction current limiting of the first fuse 1, the first switch 41 is used for controlling the on-off of the compensation resistor 42 across the first fuse 1, and the compensation resistor 42 and the first switch 41 can be set according to actual needs, and no limitation is made hereon.

[0040] The detection module 2 is used for collecting the first voltage of the first fuse 1, and the specific type of the detection module 2 can be set according to actual needs, and no limitation is made hereon. For example, the detection module 2 can be an integrated circuit based on a voltage conversion circuit.

[0041] The control module 3 is used for operation control of the compensation branch 4, and the specific type of the control module 3 can be set according to actual needs, and no limitation is made hereon. For example, the control module 3 can be a controller, a processor, etc.

[0042] The preset proportion can be a proportion corresponding to the measurement accuracy of the voltage transformer 5. For example, when the measurement accuracy is 0.002 (0.2 level), the preset proportion can be 1 / 1000; and when the measurement accuracy is 0.005 (0.5 level), the preset proportion can be 1 / 1000.

[0043] As shown in FIG. 1, Figure 2 As shown in FIG. 1,

[0044] It can be understood that, since the second fuse 43 is connected in series with the first switch 41 and the compensation resistor 42, when the first switch 41 is turned on, the compensation resistor 42 and the second fuse 43 corresponding to the first switch 41 can be connected in parallel to the first fuse 1, so as to realize voltage reduction of the first fuse 1 by using the compensation resistor 42, and when the first fuse 1 develops to be blown, the second fuse 43 can continue to protect the voltage transformer 5 as a new first fuse 1. Thus, by using the sequential operation of multiple compensation branches 4, the replacement time of the first fuse 1 can be greatly delayed while ensuring the safe operation of the voltage transformer 5 and meeting the accuracy requirement of the voltage transformer 5, thereby meeting the low-frequency replacement requirement of the first fuse 1.

[0045] It should be noted that the second fuse 43 cooperates with the first fuse 1 to realize the circuit protection of the voltage transformer 5, and the specific type of the second fuse 43 can be set according to actual needs, and no limitation is made thereto. For example, based on the fact that at most two branches of the plurality of compensation branches 4 are in operation, the second fuse 43 can have a fuse current that is one half of the fuse current of the first fuse 1.

[0046] As shown in Figure 2 some embodiments, the compensation branch 4 further includes a second switch 44 connected in series between the second end of the second fuse 43 and the second end of the first fuse 1, and the first end of the second switch 44 is connected to the second end of the second fuse 43, and the second end of the second switch 44 is connected to the second end of the first fuse 1. The signal output end of the control module 3 is connected to the signal input end of the first switch 41 and the signal input end of the second switch 44, respectively, and the control module 3 is configured to control the on-off of the plurality of first switches 41 and the plurality of second switches 44 according to the first voltage of the first fuse 1, so that the first voltage is not greater than the preset proportion of the rated voltage of the voltage transformer 5.

[0047] It can be understood that, since the second switch 44 is connected in series between the second end of the second fuse 43 and the second end of the first fuse 1, and the signal output end of the control module 3 is connected to the signal input end of the first switch 41 and the signal input end of the second switch 44, respectively, the control module 3 can control the on-off of the plurality of first switches 41 and the plurality of second switches 44 according to the first voltage of the first fuse 1, so as to realize the stable conduction or disconnection of the corresponding compensation branch 4, thereby ensuring the stable and safe operation of the voltage transformer 5.

[0048] It should be noted that the second switch 44 is used to synchronize the on-off with the first switch 41, so as to realize the double protection of the on-off control of the corresponding compensation branch 4, and the specific type of the second switch 44 can be set according to actual needs, and no limitation is made thereto.

[0049] As shown in Figure 3 some embodiments, the compensation branch 4 includes a relay, a coil 45 of the relay is connected in series on a control loop of the control module 3, and a first normally open contact of the relay is connected in series between the first end of the compensation resistor 42 and the first end of the first fuse 1 as the first switch 41, and a second normally open contact of the relay is connected in series between the second end of the second fuse 43 and the second end of the first fuse 1 as the second switch 44. The control module 3 is configured to control the on-off of the control loop according to the first voltage of the first fuse 1, so as to control the on-off of the first normally open contact and the second normally open contact in the relay.

[0050] Understandably, since the relay coil 45 is connected in series in the control circuit of the control module 3, and the first normally open contact of the relay is connected in series between the first end of the compensation resistor 42 and the first end of the first fuse 1 as a first switch 41, and the second normally open contact of the relay is connected in series between the second end of the second fuse 43 and the second end of the first fuse 1 as a second switch 44, the control module 3 can control the conduction of the corresponding control circuit according to the first voltage of the first fuse 1, thereby energizing the coil 45 of the corresponding relay and connecting the first and second normally open contacts in the relay. Thus, the corresponding compensation branch 4 is put into operation, thereby ensuring the safe operation of the voltage transformer 5 and meeting the accuracy requirements of the voltage transformer 5.

[0051] It should be noted that the relay includes a linkage coil 45 and a first normally open contact and a second normally open contact. When the relay coil 45 is energized, the first and second normally open contacts are connected; when the relay coil 45 is de-energized, the first and second normally open contacts are disconnected. The specific type of relay can be set according to actual needs and is not limited thereto.

[0052] Among them, the control module 3 has multiple control loops, and each control loop corresponds to a relay in the compensation branch 4. The control module 3 uses the on / off control of the control loops to realize the commissioning control of the corresponding compensation branch 4.

[0053] like Figure 1 and Figure 4 As shown, in some embodiments, the detection module 2 includes: an isolation transformer 21, a low-pass filter 22, and a voltage conversion unit 23. The primary side of the isolation transformer 21 is connected in parallel with the first fuse 1. The AC input terminal of the low-pass filter 22 is connected to the secondary side of the isolation transformer 21. The AC input terminal of the voltage conversion unit 23 is connected to the AC output terminal of the low-pass filter 22, and the DC output terminal of the voltage conversion unit 23 is connected to the signal input terminal of the control module 3.

[0054] It is understandable that, since the isolation transformer 21, the low-pass filter 22 and the voltage conversion unit 23 are arranged sequentially between the first fuse 1 and the control module 3, the voltage drop signal across the first fuse 1 can be transformed and isolated by the isolation transformer 21, filtered by the low-pass filter 22 and converted by the voltage conversion unit 23, and then transmitted to the control module 3, thereby enabling the control module 3 to stably obtain the first voltage of the first fuse 1.

[0055] It should be noted that the isolation transformer 21 is used for voltage reduction signal isolation, and the specific type of the isolation transformer 21 can be set according to actual needs, and no limitation is made to this. For example, the isolation transformer 21 can be an isolation transformer with a capacity of 50VA and a high insulation level, close to 1:1 or slightly lower than 1:1.

[0056] The low-pass filter 22 is used for filtering the voltage reduction signal, and the specific type of the low-pass filter 22 can be set according to actual needs, and no limitation is made to this.

[0057] The voltage conversion unit 23 is used for converting the voltage reduction signal, and specifically, for converting an alternating current signal into a direct current signal. The specific type of the voltage conversion unit 23 can be set according to actual needs, and no limitation is made to this. For example, the voltage conversion unit 23 can be a conversion circuit based on an alternating current to direct current module and a direct current to direct current module.

[0058] The adaptive resistance matrix and the isolation transformer 21 are respectively connected with the primary circuit, belong to the high-voltage part, and can be independently installed in a cabinet made of insulating materials (such as epoxy plates or acrylic plates) and installed in a PT cabinet.

[0059] The device of the embodiment is preferably installed in the PT cabinet. Since it is directly connected with the primary equipment, a high insulation level is required, and therefore the whole machine is installed with insulating materials.

[0060] Specifically, the adaptive resistance matrix and the isolation transformer 21 are respectively connected with the primary circuit, belong to the high-voltage part, and can be independently installed in a cabinet (the shell is 6mm thick) made of insulating materials (such as epoxy plates or acrylic plates) and installed in a PT cabinet. Split-phase sampling is adopted.

[0061] In the device of the embodiment, the main circuit adopts high-voltage-resistant insulating wires, an insulating sleeve, a plastic-sealed solid-state relay, and an isolation transformer for isolation of the working power supply, and the potential is suspended (not grounded).

[0062] The disclosure embodiment also provides a running method of the adaptive protection device.

[0063] S1: obtaining a first voltage of a first fuse in the device, and a rated voltage and a measurement accuracy of a voltage transformer;

[0064] S2: calculating a second voltage based on the rated voltage of the voltage transformer and according to a proportion corresponding to the measurement accuracy;

[0065] S3: comparing the first voltage and the second voltage, and when the first voltage is greater than the second voltage, issuing an alarm information and calculating a total impedance of a voltage measurement circuit in the device;

[0066] S4: calculating the maximum allowed resistance of the first fuse based on the total impedance of the voltage measurement loop and according to the proportion corresponding to the measurement accuracy;

[0067] S5: controlling the on-off of the plurality of first switches according to the maximum allowed resistance of the first fuse, so that the total resistance of the compensation resistance corresponding to the first switch that is turned on and the first fuse is less than the maximum allowed resistance of the first fuse.

[0068] It can be understood that the first voltage of the first fuse is directly detected, the second voltage is calculated according to the proportion corresponding to the measurement accuracy, and when the first voltage is greater than the second voltage, an alarm information is sent to prompt the operator to arrange maintenance in time. At the same time, the total impedance of the voltage measurement loop is calculated, and the maximum allowed resistance of the first fuse is obtained according to the proportion corresponding to the measurement accuracy. In addition, the on-off of the plurality of first switches is controlled according to the maximum allowed resistance of the first fuse, so that the total resistance of the compensation resistance corresponding to the first switch that is turned on and the first fuse is less than the maximum allowed resistance of the first fuse. When the first fuse slowly melts and develops, the compensation resistance is put into operation, which can ensure the safe operation of the voltage transformer while meeting the measurement accuracy requirement of the voltage transformer.

[0069] Among them, based on the automatic operation of the compensation branch, the replacement time of the first fuse is effectively delayed, which can adapt to the low-frequency replacement scene of the first fuse.

[0070] In addition, the control module directly obtains the voltage drop across the first fuse by using the detection module, which has higher precision and sensitivity.

[0071] In some embodiments, the method further comprises: when the first voltage is the open circuit voltage, taking the second fuse corresponding to the first switch that is turned on in the device as a new first fuse, and controlling the on-off of the remaining first switches in the device, so that the total resistance of the compensation resistance corresponding to the first switch that is turned on in the remaining first switches and the compensation resistance corresponding to the new first fuse is less than the maximum allowed resistance of the first fuse.

[0072] It can be understood that when the first voltage is the open circuit voltage, it indicates that the first fuse has developed to be blown. The second fuse corresponding to the first switch that is turned on is taken as a new first fuse, and the on-off of the remaining first switches is controlled, so that the total resistance of the compensation resistance corresponding to the first switch that is turned on in the remaining first switches and the compensation resistance corresponding to the new first fuse is less than the maximum allowed resistance of the first fuse. In this way, the safe operation of the voltage transformer is ensured while meeting the measurement accuracy requirement of the voltage transformer.

[0073] For example, the compensation branches can be set as eight groups, and the eight groups of compensation branches are sequentially put into operation in order, so that the voltage transformer is safely and stably operated, and the replacement frequency of the first fuse is greatly reduced.

[0074] In some embodiments, the method further comprises:

[0075] The on-off of the plurality of first switches in the control device is controlled, so that the total resistance of the compensation resistance corresponding to the turned-on first switch and the first fuse is one half of the maximum resistance allowed by the first fuse.

[0076] It can be understood that the total resistance of the compensation resistance corresponding to the turned-on first switch and the first fuse is reduced to one half of the maximum resistance allowed by the first fuse, thereby ensuring the effective protection of the voltage transformer after the compensation resistance is put into operation.

[0077] In some embodiments, the method further comprises:

[0078] The inductance of the voltage transformer is calculated based on the rated voltage of the voltage transformer, the three-phase load of the voltage transformer, and the direct current resistance of the voltage transformer.

[0079] The total impedance of the voltage measurement loop is calculated based on the inductance and the direct current resistance of the voltage transformer.

[0080] Specifically, the inductance of the voltage transformer is calculated based on a first formula, wherein the first formula is:

[0081] x is the inductance of the voltage transformer, U is the rated voltage of the voltage transformer, S is the three-phase load of the voltage transformer, and r is the direct current resistance of the voltage transformer.

[0082] The total impedance of the voltage measurement loop is calculated based on a second formula, wherein the second formula is: Z is the total impedance of the voltage measurement loop.

[0083] The maximum resistance allowed by the first fuse is calculated based on a third formula, wherein the third formula is: K is a proportion corresponding to the measurement accuracy, and R is the total resistance of the compensation resistance corresponding to the turned-on first switch and the first fuse.

[0084] For example, according to the specification requirements of GB / T15543-2008 “Power Quality Three-Phase Voltage Imbalance”, for the power system point of common coupling, the negative sequence voltage imbalance degree does not exceed 2% when the power grid is normally operated, and does not exceed 4% for a short time. According to the three-phase negative sequence phase vector relationship of the power system, the negative sequence component is a three times relationship of a single-phase component, a two-phase component The relationship between the negative sequence unbalance degree and the fault phase voltage difference is shown in the following table.

[0085] The target value of the normal measurement error is not greater than the national measurement level 0.2 level requirement, and the fault phase voltage difference should be less than 0.6%, and the normal phase voltage deviation is less than 0.2%.

[0086] According to the schematic diagram, an equivalent circuit diagram is prepared, as shown in Figure 5

[0087] During normal operation, the neutral point compensation resistance voltage is zero, the compensation branch is disconnected, and the impedance of the first fuse is much larger than the DC resistance of the first fuse. Therefore, the first voltage U1 of the first fuse is:

[0088]

[0089] Assuming that U1≦0.002U, the equation of R is

[0090]

[0091] After simplification, we get:

[0092] In the impedance plane, R is in the area to the straight line with a distance less than .

[0093] According to the voltage transformer parameters, and according to the annual test report and the technical parameters of the manufacturer's equipment, we calculate:

[0094] Table 1: No. 1 voltage transformer parameter table

[0095]

[0096]

[0097] Table 2: No. 2 voltage transformer parameter table

[0098]

[0099] For No. 1 voltage transformer, the proportion corresponding to the measurement accuracy is 0.002.

[0100] When r = 1.072 kΩ, U n = 18 kV, S = 600 VA, and then we get:

[0101]

[0102] Therefore, the value range of R is: ​

[0103]

[0104] to the straight line R = 4mΩ distance less than 1080Ω, namely 0≤R≤1080Ω.

[0105] And for the second voltage transformer, the corresponding proportion of measurement accuracy is 0.005.

[0106] When r = 1.060kΩ, U n = 18kV, S = 750VA,

[0107] After simplification, we get:

[0108]

[0109] to the straight line R = 50mΩ distance less than 2160Ω, namely 0≤R≤2160Ω.

[0110] That is, for the first voltage transformer, when R is less than 1080Ω, it can guarantee the accuracy higher than 0.2 level, and for the second voltage transformer, when R is less than 2160Ω, it can guarantee the accuracy higher than 0.5 level.

[0111] As Figure 6 shown, the resistance of the first fuse and the first voltage relationship diagram, it can be seen that the control target value R is less than 2160Ω, can meet the 0.5 level accuracy requirements of the second voltage transformer, corresponding to the voltage is 51.96V. That is, the adaptive matrix can be set to 51.96V, according to the principle of equal distribution of compensation resistance, and send the corresponding signal. If the compensation resistance is 2160Ω, its fuse capacity is 0.5I, and the voltage drop is reduced to 25.98V again.

[0112] When the first 2160Ω is put in, if the main fuse is blown, the voltage measurement value reaches 51.96V again, at this time, the adaptive matrix is again, and the second branch 2160Ω is again put in according to the principle of equal distribution of current, at this time, the voltage drop is reduced to 25.98V again. At this time, if the first input path is caused by the fuse to melt or the resistance itself, the adaptive matrix device is again, and the equal distribution of compensation resistance is again put in, and so on.

[0113] The device of the embodiment has mature technology and low manufacturing cost, can monitor the working state of the PT fuse online, timely input the adaptive compensation loop when the slow melting process of the PT fuse is developed, and alarm, so as to ensure that the PT measurement loop is kept within the precision requirement, avoid the influence of the PT fuse blown on the normal work of the protection and measurement and control device, and solve the loss caused by the measurement error and the safety risk caused by the protection failure due to the slow melting of the PT fuse.

[0114] It should be noted that in the description of the present disclosure, the terms "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In addition, in the description of the present disclosure, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0115] Any process or method descriptions in flow charts or described elsewhere herein can be understood as representing code modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions (or steps) in the process, and that the scope of the preferred embodiments of the present disclosure encompasses alterations, modifications, and variations of these code modules, segments, or portions of code that can be performed in an order different than the order that is shown or discussed. Such variations, alterations, and modifications are intended to fall within the scope of the present disclosure.

[0116] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0117] Although the embodiments of the present disclosure have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present disclosure, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present disclosure.

Claims

1. An adaptive arming device for a voltage transformer, characterized in that The application relates to a voltage measurement circuit of a bus, which comprises: a first fuse connected in series with a voltage transformer in a voltage measurement loop of a bus; a plurality of compensation branches connected in parallel at both ends of the first fuse, wherein each compensation branch comprises a first switch and a compensation resistor connected in series between the first end and the second end of the first fuse; a detection module connected to the first fuse and configured to collect a first voltage of the first fuse; a control module connected to a signal output end of the detection module and a signal input end of the first switch, and configured to control the on-off of the first switches according to the first voltage of the first fuse, so that the first voltage is not greater than a preset proportion of the rated voltage of the voltage transformer.

2. An adaptive protection device for a voltage transformer according to claim 1, characterized in that, The compensation branch further comprises: a second fuse connected in series with the first switch and the compensation resistor, wherein the first end of the first switch is connected to the first end of the first fuse, the first end of the compensation resistor is connected to the second end of the first switch, the second end of the compensation resistor is connected to the first end of the second fuse, and the second end of the second fuse is connected to the second end of the first fuse.

3. An adaptive protection device for a voltage transformer according to claim 2, characterised in that, The compensation branch further comprises: a second switch connected in series between the second end of the second fuse and the second end of the first fuse, wherein the first end of the second switch is connected to the second end of the second fuse, and the second end of the second switch is connected to the second end of the first fuse; wherein the signal output end of the control module is connected to the signal input end of the first switch and the signal input end of the second switch, and the control module is configured to control the on-off of the first switches and the second switches according to the first voltage of the first fuse, so that the first voltage is not greater than a preset proportion of the rated voltage of the voltage transformer.

4. An adaptive protection device for a voltage transformer according to claim 3, characterised in that, The compensation branch comprises: a relay, wherein the coil of the relay is connected in series in a control loop of the control module, the first normally open contact of the relay is connected in series between the first end of the compensation resistor and the first end of the first fuse as the first switch, and the second normally open contact of the relay is connected in series between the second end of the second fuse and the second end of the first fuse as the second switch; wherein the control module is configured to control the on-off of the control loop according to the first voltage of the first fuse, so as to control the on-off of the first normally open contact and the second normally open contact of the relay.

5. The adaptive protection device for a voltage transformer according to claim 1, characterized in that, The detection module comprises: an isolation transformer connected in parallel to the first fuse on a primary side; a low-pass filter with an alternating current input end connected to a secondary side of the isolation transformer. A voltage conversion unit, an AC input end of the voltage conversion unit being connected with an AC output end of the low-pass filter, and a DC output end of the voltage conversion unit being connected with a signal input end of the control module.

6. A method for operating an adaptive protection device of a voltage transformer according to any one of claims 1-5, comprising: obtaining a first voltage of a first fuse in the device, a rated voltage of the voltage transformer, and a measurement accuracy; calculating a second voltage based on the rated voltage of the voltage transformer and according to a ratio corresponding to the measurement accuracy; comparing the first voltage and the second voltage, and when the first voltage is greater than the second voltage, issuing an alarm and calculating a total impedance of a voltage measurement loop in the device; calculating a maximum allowed resistance of the first fuse based on the total impedance of the voltage measurement loop and according to the ratio corresponding to the measurement accuracy; controlling on-off of a plurality of first switches in the device according to the maximum allowed resistance of the first fuse, so that a total resistance of a compensation resistance corresponding to the first switch that is turned on and the first fuse is less than the maximum allowed resistance of the first fuse.

7. A method of operating an adaptive protection device for a voltage transformer according to claim 6, characterized in that, The method further comprises: when the first voltage is an open circuit voltage, taking a second fuse corresponding to the first switch that is turned on in the device as a new first fuse, and controlling on-off of the remaining first switches in the device, so that a total resistance of a compensation resistance corresponding to the first switch that is turned on among the remaining first switches and a compensation resistance corresponding to the new first fuse is less than the maximum allowed resistance of the first fuse.

8. The method of operation of the adaptive protection device of a voltage transformer according to claim 6, characterized in that, The method further comprises: controlling on-off of a plurality of first switches in the device, so that a total resistance of a compensation resistance corresponding to the first switch that is turned on and the first fuse is half of the maximum allowed resistance of the first fuse.

9. The method of operation of the adaptive protection device of a voltage transformer according to claim 6, characterized in that, The method further comprises: calculating a reactance of the voltage transformer based on the rated voltage of the voltage transformer, a three-phase load of the voltage transformer, and a DC resistance of the voltage transformer; calculating the total impedance of the voltage measurement loop based on the reactance and the DC resistance of the voltage transformer.

10. A method of operating an adaptive protection device for a voltage transformer according to claim 9, characterized in that, The method further comprises: The inductance of the voltage transformer is calculated based on a first formula, wherein the first formula is: The x is the inductance of the voltage transformer, the U is the rated voltage of the voltage transformer, the S is the three-phase load of the voltage transformer, and the r is the DC resistance of the voltage transformer. calculating a total impedance of the voltage measurement loop based on a second formula, wherein the second formula is: the Z is a total impedance of the voltage measurement loop; The allowed maximum resistance of the first fuse is calculated based on a third formula, wherein the third formula is: The K is a proportion corresponding to the metering accuracy, and the R is a total resistance of a compensation resistance corresponding to the first switch in conduction and the first fuse.

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