JP6253995B2 - Input converter and input conversion board of digital protection control device - Google Patents

Description

  The present invention relates to an input converter and an input conversion board of a digital protection control device, and more particularly to an input of a digital protection control device that takes in an output from an input transformer that measures an electric quantity of a power system and performs protection control of the power system. It is suitable for application to a converter and an input conversion board.

  In a digital protection control device used for power system protection control, an input unit for taking in an output from an input transformer that measures the voltage and current of the power system, and protection control calculation by executing protection control calculation The control unit that performs is configured as a separate unit as exemplified in Patent Document 1.

  In the current transformer used for the input converter of the digital protection control device in the power system, when a power system fault occurs, it can improve the resistance to DC bias due to the transient DC component, It is important to improve accuracy. Further, since the input transformer of the digital protection control device is composed of a plurality of input transformers which are high-voltage parts, it occupies a large installation capacity in the protection control plate. For this reason, current transformers are also required to be smaller and lighter.

JP-A-8-163766

  In order to improve the resistance to DC bias due to excessive DC components, it is necessary to increase the size of the coil. By increasing the size of the coil core, however, the current transformer can be reduced in size and cost. It becomes difficult. In addition, even if a DC bias due to a transient DC component occurs, it is possible to use an EI core that has a gradual saturation characteristic due to leakage flux, but the accuracy deteriorates due to inferior excitation impedance compared to a toroidal core. There was a problem that.

  The present invention has been made in view of the above points. The EI core is used to improve the resistance against DC bias due to the transient DC component, the core is downsized, and the iron core of the EI core is hybridized to maintain the excitation impedance. It is an object of the present invention to propose an input converter and an input conversion board for a digital protection control device that can be used.

In order to solve such a problem, in the present invention, an input converter of a digital protection control device that performs protection control of a power system, wherein the input converter includes an input transformer that measures an electrical quantity of the power system, an input unit for taking in the output from the input transformer is composed of the input transformer, Ri Do from EI core hybridized to the core, the core of the EI core, silicon steel sheets to sandwich permalloy And configured .
According to the present invention, there is provided an input conversion board constituting an input converter of a digital protection control device, wherein the input conversion board is wound around a primary circuit for inputting a current from a power system and an iron core of an EI core. A coil that converts a current input to the primary circuit into a predetermined ratio and outputs the coil to a secondary circuit, and a secondary circuit that converts an output current from the coil into a voltage. The iron core is configured such that a silicon steel plate is sandwiched between permalloys.

  According to such a configuration, an EI core having a leakage flux larger than that of the toroidal core is adopted as the input transformer, and an improvement in direct current demagnetization resistance due to a transient direct current component in the current transformer of the digital protection control device can be realized. In addition, the accuracy of a small current input can be improved by hybridizing the iron core.

  According to the present invention, the EI core can improve the resistance against direct-current bias due to the transient DC component, downsize the core, and hybridize the iron core of the EI core to maintain the excitation impedance.

It is a conceptual diagram explaining the structure of EI core which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the structure of the input converter of the digital protection control apparatus concerning the embodiment. It is a block diagram which shows the circuit structure of the input converter of the digital protection control apparatus concerning the embodiment. It is a graph explaining evaluation of the number ratio of the iron core hybrid concerning the embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Overview of this embodiment First, an overview of this embodiment will be described. As described above, in the current transformer used for the input converter of the digital protection control device in the power system, when a power system fault occurs, it is possible to improve the resistance to DC bias due to the transient DC component, It is required to improve the accuracy when power is input. In addition, miniaturization and weight reduction of current transformers are also required.

  As described above, the digital protection control device includes an input unit (input converter) that takes in an output from the input transformer of the power system and a control unit that performs protection control of the power system. In the conventional input conversion unit, it is necessary to increase the size of the coil as a measure for improving the resistance to DC bias due to the transient DC component. However, when the coil core becomes large, there is a problem that it is difficult to reduce the size and cost of the current transformer. In particular, the toroidal core of grain-oriented silicon steel plate has a drawback that the magnetic flux is saturated suddenly. When a transient direct current is input, the direct current is easily demagnetized and the distortion of the output waveform is increased.

  Therefore, it is conceivable to use an EI core having a gentle saturation characteristic due to leakage magnetic flux even if a DC bias due to a transient DC component occurs. However, the accuracy of the EI core is inferior to that of a toroidal core. Deteriorate.

  Therefore, in the present embodiment, the EI core is used to improve the resistance against DC bias due to the transient DC component, and the core can be downsized, and the iron core of the EI core can be hybridized to maintain the excitation impedance.

  Specifically, by adopting an EI core having a larger leakage magnetic flux than the toroidal core, and using a non-oriented silicon steel plate having mild saturation characteristics or PB permalloy containing 48% NI for the core material of the EI core, Improving the resistance to DC bias due to the transient DC component in the CT circuit (current transformer) of the digital protection controller. Moreover, the precision with a small electric current input is improved by adopting the hybrid iron core comprised from a silicon steel plate and PC permalloy.

  As described above, by adopting the small EI core, the leakage magnetic flux is increased and a gentle saturation characteristic is obtained. As a result, even if the DC bias is generated due to the transient DC component, the output distortion, that is, the difference or distortion of the output waveform with respect to the input waveform can be reduced.

  In addition, a non-oriented silicon steel sheet with a gentle saturation characteristic is adopted as the core material of the core. An EI core using a non-oriented silicon steel sheet has lower excitation impedance than a conventional core. Therefore, in this embodiment, the iron core of the EI core is hybridized to maintain the excitation impedance, that is, the accuracy of the low input range even if the EI core is minimized.

  Specifically, in the present embodiment, the number ratio of the EI core iron core hybrid is 90% silicon steel plate and 10% PC permalloy. Further, when the core is made into a laminated iron core and hybridized, a structure in which the silicon steel plate is sandwiched between permalloys is used to inductively balance the magnetic flux flow on both sides of the core.

  Further, by reducing the diameter of the winding of the EI core and increasing the number of turns to about 2.5 times, it is possible to maintain an excitation impedance equal to or higher than that when a toroidal core is adopted. In addition, when the EI core is adopted, the winding work is performed on the bobbin, the workability of the winding is improved, and the number of turns can be increased, so that the core can be downsized. Since the core is downsized, the volume ratio can be halved as compared with the conventional digital protection control device, and the size and cost of the device can be reduced.

(2) Configuration of EI Core Next, the configuration of the EI core according to the present embodiment will be described with reference to FIG. An external view 100 of FIG. 1 is a perspective view of an EI core 102 around which a coil 101 is wound. As shown in the external view 100 of FIG. 1, the coil 101 is wound around the bobbin of the EI core 102.

  An external view 110 in FIG. 1 is a view as seen from the upper surface of the EI core 102. As shown in an external view 110 of FIG. 1, a hybrid iron core in which a PC permalloy 103 and a silicon steel plate 104 are laminated is adopted as the iron core of the EI core 102. The number ratio of the PC permalloy 103 and the silicon steel plate 104 is, for example, 10% for the PC permalloy 103 and 90% for the silicon steel plate 104. Thus, by adopting a hybrid iron core for the EI core 102, the accuracy of the low input range can be maintained.

  Further, as shown in the external view 110 of FIG. 1, by adopting a configuration in which the silicon steel plate 104 is sandwiched between the PC permalloy 103, the flow of the magnetic flux can be made uniform on both sides of the EI core 102 and inductively balanced. it can.

  Further, in this embodiment, as shown in the external view 100 of FIG. 1, the winding diameter of the EI core 102 is made thinner, and the number of turns is increased by about 2.5 times compared to the conventional core. As a result, it is possible to maintain an excitation impedance equal to or higher than that in the case where a conventional toroidal core is adopted while downsizing the core.

  Here, the case where the excitation impedance cannot be maintained means that the EI core 102 is magnetically saturated. By reducing the size of the EI core, the cross-sectional area of the core is reduced, but by increasing the number of turns, it is possible to maintain the magnetic saturation voltage. In this embodiment, when the size of the EI core is reduced, the core cross-sectional area is physically reduced to 1 / 2.5, so the number of turns is 2.5 times. However, the number of turns is 2.5 times or more. Thus, the excitation impedance can be maintained. In addition, since the volume of an electric wire is required, so that there are many turns, you may make it design considering the physical volume in consideration of size reduction of the cross-sectional area of a core, and determination of the number of turns of a coil.

(3) Configuration of Input Converter of Digital Protection Control Device Next, the configuration of the input converter of the digital protection control device will be described with reference to FIG. FIG. 2 shows a state in which a plurality of input transformers composed of EI cores are accommodated. 2 is a side view of the input converter, and FIG. 11 is a plan view of the input converter.

  As shown in FIG. 2, in the input converter of the digital protection control device, the printed board 16 is fixed to the position of the frame portion of the reinforcing bracket 17 with screws 12 and 14 at various places. The print board 16 includes an input connector 15 including 16 terminals and an output connector 13.

  By arranging a plurality of input transformers composed of the EI core 102 around which the coil 101 is wound as shown in FIG. 2, the coils are not affected by the magnetic flux between each other.

(4) Circuit Configuration Next, the circuit configuration of the input converter of the digital protection control device will be described with reference to FIG. As described above, the input converter of the digital protection control device converts the level of the signal detected by the current transformer or the voltage transformer, etc., from the current or voltage of the transmission line or the like to be protected by the input transformer, It has a function of insulating and taking in the inside.

  As shown in FIG. 3, the circuit of the input converter includes a primary circuit 210, a coil 101, and a secondary circuit 220. The input of the primary circuit 210 is set to the winding ratio of the coil 101 and is output to the secondary circuit 220. On the secondary circuit 220 side, the output current of the coil 101 is converted into a voltage by the resistor R. For example, the input converter inputs AC10A to 200A from the primary circuit and outputs AC10Vmax to the secondary circuit. Further, the ground E is configured so that the noise of the primary circuit 210 does not transfer to the secondary circuit 220.

(5) Evaluation of the number ratio of iron core hybrids Next, with reference to FIG. 4, evaluation of the number ratio of iron core hybrids employed in the EI core will be described. FIG. 4 is a graph showing the relationship between the number ratio of permalloy and the input / output characteristics. FIG. 4 shows a characteristic graph when the ratio of the number of permalloy sheets is large, medium, and small as compared with the graph of ideal characteristics. In this embodiment, when the ratio of the number of permalloy is large, the ratio of the number of permalloy is 20% or more of the whole, and when the ratio of the number of permalloy is medium, the ratio of the number of permalloy is 10 to 20% of the whole. When the ratio of the number of permalloy is small, the ratio of the number of permalloy is set to 10% or less of the whole.

  As shown in FIG. 4, when the ratio of the number of permalloys is large, the excitation impedance in the low input region becomes higher than the excitation impedance in the high input region, so that the input / output characteristics are not uniform. In this case, the accuracy of the low input is good, but the accuracy of the high input is deteriorated.

  It can also be seen that when the ratio of the number of permalloys is medium, the excitation impedance in the low input region and the excitation impedance in the high input region are constant, and the input / output characteristics are uniform. In this case, it can be seen that the accuracy of the low input and the high input is the same.

  When the ratio of the number of permalloys is small, the excitation impedance in the low input region is lower than the excitation impedance in the high input region, and the input / output characteristics are not uniform. In this case, it can be seen that the accuracy of the low input is poor and the accuracy of the high input is good.

  Therefore, it can be seen that the evaluation is closest to the ideal characteristic when the ratio of the number of permalloy sheets is medium. Therefore, in this embodiment, the number ratio of the EI core iron core hybrid is 90% silicon steel plate and 10% PC permalloy.

  Further, as described above, by arranging the PC permalloy on both sides of the silicon steel plate, the flow of magnetic flux can be made uniform on both sides of the core and balanced inductively. In the present embodiment, the silicon steel plate is sandwiched between PC permalloys. Moreover, although the method of arrange | positioning PC permalloy symmetrically and the method of arrange | positioning in the center are also considered, productivity of EI core can be improved by setting it as the structure which sandwiches a silicon steel plate with PC permalloy.

  Also, the EI core hybrid iron core can be made of another magnetic material such as a directional silicon steel plate or finemet. For example, when a grain-oriented silicon steel plate is used, the overall excitation impedance increases, but the saturation voltage decreases and the cost increases. In addition, even when Finemet is used, the excitation impedance as a whole increases and the saturation voltage also increases, but the cost increases.

(6) Effects of the present embodiment As described above, according to the present embodiment, by adopting a small EI core, the workability of the winding is improved and the number of turns is about 2.5 times that of the conventional one. As a result, it is possible to reduce the size of the core while ensuring the accuracy of the core, that is, the desired excitation impedance.

101 Coil 102 EI Core 103 PC Permalloy 104 Silicon Steel

Claims (3)

An input converter of a digital protection control device that performs protection control of a power system,
The input converter is
An input transformer that measures the amount of electricity in the power system;
An input unit for capturing the output from the input transformer;
Consisting of
Wherein the input transformer, Ri Do from EI core hybridized an iron core,
The iron core of the EI core is
An input converter for a digital protection control device, characterized in that the silicon steel plate is sandwiched between permalloys . The iron core of the EI core is
2. The input converter for a digital protection control device according to claim 1 , wherein the input converter is hybridized at a number ratio of 90% silicon steel plate and 10% permalloy . An input conversion board constituting an input converter of a digital protection control device,
The input conversion board is:
A primary circuit that inputs current from the power system;
A coil that is wound around an iron core of an EI core, converts the current input to the primary circuit into a predetermined ratio, and outputs the current to the secondary circuit;
A secondary circuit for converting an output current from the coil into a voltage;
Equipped with a,
The iron core of the EI core is
Constructed by sandwiching a silicon steel plate with permalloy
An input conversion board characterized by that.

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