Switchboards equipped with lossless voltage transformer

Abstract

A switchgear equipped with a lossless measuring transformer is disclosed. The lossless measuring transformer of a 3-electrode double cylindrical structure comprises a high-voltage round bar electrode for voltage detection, a cylindrical voltage divider electrode arranged to surround the high-voltage round bar electrode and block voltage or electric field interference from other external phases, a polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode, a cylindrical shielding electrode arranged to surround the cylindrical voltage divider electrode and block external voltage or electric field interference, a polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode, a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with the capacitor inserted between the cylindrical voltage divider electrode and ground.

Description

Technology Field

[0001] The present invention relates to an energy-saving, eco-friendly switchgear equipped with a lossless voltage transformer (LVT). Background Technology

[0002] With the advent of the Fourth Industrial Revolution based on electric energy and the rapid increase in artificial intelligence (AI) technology and data centers, the digitalization of power systems and substations is required worldwide to ensure a stable and high-efficiency supply of electric energy. Consequently, research is actively underway on reducing power consumption, miniaturizing, and making power equipment more eco-friendly, as well as preventing power outages and electric shock accidents.

[0003] FIGS. 1a to 1f are drawings for explaining a wound core type instrument transformer (Potential Transformer; PT) according to the prior art.

[0004] Iron-core instrument transformers must be mandatorily installed as shown in FIGS. 1a to 1f within high-voltage and extra-high-voltage enclosed switchgear for system voltage measurement and protective relay operation for undervoltage or overvoltage. FIG. 1a shows the equivalent circuit of a wound-core instrument transformer according to the prior art, and FIG. 1b is a drawing showing a photograph of a wound-core instrument transformer according to the prior art. FIG. 1c is a drawing showing an example before conversion to a PIVT, and FIG. 1d is a drawing showing an example after conversion to a lossless measuring transformer. FIG. 1e shows an installation cross-sectional view (side view) of a wound-core instrument transformer according to the prior art, and FIG. 1f is a drawing showing an installation photograph of an iron-core instrument transformer according to the prior art.

[0005] In the conventional iron core type instrument transformer, voltage division is achieved by electromagnetic induction in a magnetic circuit composed of an iron core and windings. As shown in FIG. 1a, the primary winding (N1) of the instrument transformer according to the conventional technology is directly connected to the high-voltage terminal (U), making electrical insulation impossible; therefore, ground faults or short-circuit accidents frequently occur due to insulation breakdown in the primary high-voltage connection parts (111, 112, 113) inside the instrument transformer.

[0006] According to the 2024 electrical accident statistical analysis (accident statistics by equipment) by the Korea Electrical Safety Corporation, accidents caused by instrument transformers account for 11.1% of extra-high voltage and 8% of high voltage. Since this covers all indoor and outdoor high and extra-high voltage facilities, the accident rate caused by instrument transformers would increase further if limited to high and extra-high voltage switchgear. Prior art literature

[0007] Korean Registered Patent No. 10-1757753 (July 7, 2017) The problem to be solved

[0008] The technical problem that the present invention aims to solve is to propose a lossless measuring transformer and install it in a switchboard to replace the existing wound-core type instrument transformer. Unlike the existing wound-core type instrument transformer, the proposed lossless measuring transformer uses a non-contact voltage measurement method and is completely electrically isolated from the primary charging part (in other words, the connection part where voltage is applied), thereby completely preventing accidents caused by insulation breakdown. Furthermore, by equipping a lossless measuring transformer that does not use an iron core or copper wire and thus has no iron loss or copper loss, the invention aims to realize an energy-saving, eco-friendly switchboard. means of solving the problem

[0009] The present invention provides a lossless measuring transformer with a 3-electrode double cylindrical structure.

[0010] In one embodiment of the present invention, a lossless measurement transformer comprises a high-voltage rod electrode installed at the center of a cylinder, a cylindrical voltage divider electrode separated from the high-voltage rod electrode for voltage detection by a polymer insulator, a polymer insulator for separating the high-voltage rod electrode for voltage detection from the cylindrical voltage divider electrode, a cylindrical shielding electrode separated from the cylindrical voltage divider electrode by a polymer insulator for blocking voltage or electric field interference from another external phase, a polymer insulator for separating the cylindrical shielding electrode for blocking external voltage or electric field interference from the cylindrical voltage divider electrode, a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with the capacitor inserted between the cylindrical voltage divider electrode and ground.

[0011] In one embodiment of the present invention, the lossless measuring transformer has a capacitance between a high-voltage round bar electrode for voltage detection and a cylindrical voltage divider electrode separated by an insulator ( C h ) and the capacitance of the capacitor between the cylindrical voltage divider electrode and ground ( C L The partial pressure ratio is stably maintained using the negative temperature coefficient of ).

[0012] In one embodiment of the present invention, the lossless measurement transformer has a matching impedance ( R b By using ), the phase synchronization of the measured voltage is adjusted by adding the resistive current of the matching impedance to the capacitive current of the capacitor.

[0013] In one embodiment of the present invention, the lossless measuring transformer sets the output voltage to 10,000:1 of the primary high voltage, thereby eliminating any risk of electric shock even when in direct contact with the human body from 13.2kV ​​to 1.32V (※ The secondary output voltage of conventional wound-core type instrument transformers is 110V, which causes electric shock accidents upon contact with the human body).

[0014] In one embodiment of the present invention, the lossless measuring transformer does not use an iron core and can replace all existing rated 25kV, 7.2kV, and 3.6kV wound-core instrument transformers with a single rating (model) on a 1:1 basis.

[0015] In one embodiment of the present invention, by replacing it with a lossless measuring transformer, it is made smaller and lighter, thereby reducing the installation space and making it possible to secure the necessary clearance space and insulation distance for voltage measurement.

[0016] The present invention provides a switchboard equipped with a lossless measuring transformer having a 3-electrode double cylindrical structure.

[0017] In one embodiment of the present invention, the switchgear includes a high-voltage busbar and a lossless measuring transformer with a 3-electrode double cylindrical structure configured to measure the voltage of the busbar.

[0018] The present invention provides a voltage measurement method using a lossless measuring transformer with a 3-electrode double cylindrical structure.

[0019] In one embodiment of the present invention, a voltage measurement method comprises the steps of: applying a voltage to be measured to a high-voltage rod electrode; dividing the voltage to be measured by a capacitance formed between the high-voltage rod electrode and a cylindrical voltage divider electrode, a capacitor connected between the cylindrical voltage divider electrode and a cylindrical shielding electrode, and a capacitor inserted between the cylindrical voltage divider electrode and ground to generate a voltage divider voltage at the cylindrical voltage divider electrode; correcting a phase error of the voltage divider voltage using a matching impedance; and detecting the voltage divider voltage output from the cylindrical voltage divider electrode to calculate the voltage to be measured. Effects of the invention

[0020] According to one embodiment of the present invention, a lossless measuring transformer is installed in a switchboard to replace a conventional iron core type instrument transformer. Unlike conventional iron core type instrument transformers, the proposed lossless measuring transformer uses a non-contact capacitive voltage divider method and is completely electrically isolated from the primary charging part (in other words, the connection part to which voltage is applied), thereby completely preventing accidents caused by insulation breakdown. Since it does not use an iron core or copper wire, it is possible to miniaturize and lighten it to 1 / 25 the weight and 1 / 8 the volume compared to conventional iron core type PTs of the same rating, enabling the compactness of the switchboard. Furthermore, since iron loss and copper loss do not occur, it can contribute significantly to preventing electrical safety accidents and carbon neutrality through energy savings in the switchboard. Brief explanation of the drawing

[0021] FIGS. 1a to 1f are drawings for explaining a wound core type instrument transformer according to the prior art. FIG. 2 is a diagram illustrating the voltage detection principle of a lossless measurement transformer according to one embodiment of the present invention. FIG. 3 is a diagram illustrating the voltage division ratio error and phase error according to temperature of a lossless measurement transformer according to one embodiment of the present invention. FIG. 4 is a drawing illustrating a lossless measuring transformer according to one embodiment of the present invention. FIG. 5 is a diagram illustrating a voltage detection method for a lossless measurement transformer according to one embodiment of the present invention. FIG. 6 is a diagram illustrating a power fuse (PF) for protecting a wound core type instrument transformer according to the prior art. FIG. 7 is a drawing for comparing a switchboard with a wound core type instrument transformer according to the prior art and a switchboard with a PT board omitted when a lossless measuring transformer according to the present invention is applied. Figure 8 is a drawing for explaining the installation restriction regulations for iron core type instrument transformers, showing a single-line diagram of a substation facility. FIG. 9 is a drawing illustrating the installation of a lossless measuring transformer according to the present invention within a switchboard. FIG. 10 is a diagram illustrating power components in a lossless measurement transformer according to one embodiment of the present invention. Specific details for implementing the invention

[0022] In the conventional technology, the wound core instrument transformer is structured to be directly electrically connected to the primary high-voltage terminal, and insulation breakdown accidents frequently occur due to constant electrical stress during operation.

[0023] In this invention, a lossless measuring transformer is proposed that incorporates a non-contact voltage divider electrode completely insulated from a high-voltage terminal and a polymer epoxy insulator. By replacing and applying the existing iron-core instrument transformer in the switchgear, electrical insulation breakdown is fundamentally blocked, thereby ensuring safety by preventing insulation breakdown caused by high-voltage electric field stress inside the switchgear. At the same time, the output voltage of the lossless measuring transformer is AC 1.32V or less (the safety limit voltage of AC 30V or less according to the Korean Occupational Safety and Health Act), so there is no risk of electric shock to the human body even with direct contact.

[0024] According to one embodiment of the present invention, safety can be ensured by preventing insulation accidents, and unlike conventional wound-core instrument transformers (power loss: iron loss + copper loss = 5~30VA), the power loss for voltage measurement is almost zero (0), thereby contributing to energy saving effects and global carbon neutrality. In addition, as a compact and lightweight lossless measurement transformer, space in the switchgear can be secured (compact and lightweight, with a weight 1 / 20 and volume 1 / 8 compared to existing wound-core instrument transformers of the same rating), and cost reduction and production processes can be improved. Hereinafter, one embodiment of the present invention will be described in detail with reference to the attached drawings.

[0025] FIG. 2 is a diagram for explaining the voltage detection principle of a lossless measurement transformer according to an embodiment of the present invention, where FIG. 2(a) is a cross-sectional view of an electrode system and FIG. 2(b) is an equivalent circuit. FIG. 3 is a diagram for explaining the voltage division ratio error and phase error according to temperature of a lossless measurement transformer according to an embodiment of the present invention.

[0026] In the equivalent circuit of a lossless measurement transformer according to one embodiment of the present invention, the capacitance generated between a high-voltage round bar electrode for voltage detection and a cylindrical voltage divider electrode separated by an insulator C h and the capacitance generated between the voltage divider electrode and the grounded shielded electrode C L , and the capacitance of the capacitor inserted in parallel with it C b Partial pressure is achieved by

[0027] According to one embodiment of the present invention, C h The capacitance of can be calculated using the following [Equation 1] if the edge effect at the electrode is ignored.

[0028]

[0029] Here, e 0 is the permittivity of vacuum, and e s is the relative permittivity of the epoxy insulator constituting the capacitance, and a is the radius of the high-voltage round rod electrode, b and l is the radius and length of the electrode.

[0030] also C L The capacitance of can be calculated using the following [Equation 2].

[0031]

[0032] Here, c is the radius of the cylindrical shielding electrode. These C h and C L The value of depends on the radius and length of the cylindrical electrode.

[0033] In Fig. 2(b), the partial pressure ratio C b It is adjusted, and at this time, the divided secondary voltage V out It is equal to the following [Mathematical Formula 3].

[0034]

[0035] Meanwhile, the capacitance constituting the voltage divider circuit in the above [Equation 1] and [Equation 2] C h and C L Fluctuations in the partial pressure ratio occur due to changes in relative permittivity (temperature coefficient) caused by changes in ambient temperature, and C h and C L The temperature coefficient can be controlled by adjusting the sintering temperature and sintering time of the sintering process.

[0036] High voltage capacitance ( C h ) and low-voltage capacitance( C L The temperature coefficient (+) of the relative permittivity of ) is the same, and the capacitor ( connected to the low-voltage section for adjusting the voltage division ratio) C b By applying the principle that the dielectric constant of the dielectric constant of the insulating material has a linear temperature coefficient (-) that is inversely related to the dielectric constant of the insulating material, the difference in voltage division ratio due to temperature change was completely resolved physically without a separate temperature compensation circuit. By offsetting the change in capacitance due to temperature change, as shown in Fig. 3, it was possible to sufficiently maintain a voltage division ratio error of 0.2% and a phase error of within 10 min in the operating conditions of a measurement transformer with an accuracy of 0.2 class, ranging from -25℃ to +40℃.

[0037] The voltage division ratio of the lossless measurement transformer proposed in this invention is a capacitor C b By adjusting the value, the ratio can be set to a desired ratio such as 100:1, 1,000:1, 10,000:1, and 100,000:1, depending on the rated voltage rating from low voltage to high voltage or special high voltage.

[0038] also R b is the matching impedance, ( C L + C b ) to the capacitive current R b It serves to synchronize with the phase of the primary high voltage by adding a resistive current and to match the input impedance (2 MΩ) of the digital electrical information observation device.

[0039] FIG. 4 is a drawing illustrating a lossless measurement transformer according to one embodiment of the present invention, where FIG. 4 (a) is a schematic cross-sectional view, FIG. 4 (b) is a photograph of a molded electrode system module, and FIG. 4 (c) is a photograph of a lossless measurement transformer.

[0040] A lossless measuring transformer comprises a high-voltage rod electrode (410) connected to a high-voltage terminal (400) for voltage detection and a cylindrical voltage divider electrode (420) separated by an insulating material (411), a polymer insulating material (411) for separating the high-voltage rod electrode (410) and the cylindrical voltage divider electrode (420), a cylindrical shielding electrode (430) separated by a polymer insulating material (411) for blocking voltage or electric field interference from an external other phase, a polymer insulating material (411) for separating the cylindrical shielding electrode (430) for blocking external voltage or electric field interference and the cylindrical voltage divider electrode (420), a capacitor connected between the cylindrical voltage divider electrode (420) and the cylindrical shielding electrode (430), and a capacitor inserted between the cylindrical voltage divider electrode (420) and ground. Matching impedances connected in parallel ( R b Includes ).

[0041] According to one embodiment of the present invention, the capacitance between a high-voltage rod electrode (410) for voltage detection and a cylindrical voltage divider electrode (420) separated by an insulating material ( C h ) and the capacitance (C) of the capacitor between the cylindrical voltage divider electrode (420) and ground L A matching impedance ( R b By using ), the phase synchronization of the measured voltage can be controlled by adding the resistive current of the matching impedance to the capacitive current of the capacitor.

[0042] According to one embodiment of the present invention, the lossless measuring transformer with a 3-electrode double cylindrical structure does not use copper windings and an iron core, and must manufacture a wound-core type instrument transformer for each rated voltage (24kV, 13.2kV, 7.2kV, and 3.6kV) of the existing wound-core type instrument transformer, but the lossless measuring transformer of the present invention can replace all of the following ratings on a 1:1 basis with a single rating of 24kV.

[0043] In addition, by setting the output voltage of the lossless measuring transformer to 10,000:1 of the primary high voltage, the voltage drops from 13.2kV ​​to 1.32V, eliminating any risk of electric shock even with direct human contact. In contrast, the secondary output voltage of conventional wound-core instrument transformers is 110V, posing a risk of electric shock upon human contact.

[0044] The following [Table 1] compares the geometric specifications of the lossless measuring transformer for extra-high voltage proposed in this invention with those of a conventional wound-core instrument transformer of the same rating. Conventional wound-core instrument transformers may vary slightly depending on the manufacturer.

[0045]

[0046] The lossless measuring transformer of the present invention, intended to replace existing wound-core instrument transformers, is made smaller and lighter by reducing the height by 55%, the installation cross-sectional area by 25%, and the weight by 5% (1 / 20) compared to a 24kV instrument transformer of the same rating, thereby reducing the installation space within the switchgear and making it possible to secure the necessary space and insulation distance for voltage measurement.

[0047] FIG. 5 is a diagram illustrating a voltage detection method for a lossless measurement transformer according to one embodiment of the present invention.

[0048] Referring to FIG. 5, in step 510, the lossless measuring transformer applies the voltage to be measured to the high-voltage round bar electrode (410).

[0049] Next, in step 520, the lossless measuring transformer has a capacitance ( formed between the high-voltage round bar electrode (410) and the cylindrical voltage divider electrode (420) C h The voltage to be measured is divided by a capacitor connected between the cylindrical voltage divider electrode (420) and the cylindrical shielding electrode (430), and a capacitor inserted between the cylindrical voltage divider electrode (420) and ground, thereby generating a divided voltage at the cylindrical voltage divider electrode (420). Here, the lossless measurement transformer is the capacitance ( between the high-voltage round bar electrode (410) and the cylindrical voltage divider electrode (420). C h The capacitance of the capacitor inserted between the cylindrical voltage divider electrode (420) and ground ( C L The partial pressure ratio is maintained using the negative temperature coefficient of ).

[0050] Next, in step 530, the lossless measurement transformer has a matching impedance ( R b The phase error of the divided voltage is corrected using ). Here, the lossless measurement transformer has a matching impedance ( R b Using ), the matching impedance ( R b The phase synchronization of the voltage to be measured is adjusted by adding a resistive current.

[0051] Next, in step 540, the lossless measuring transformer detects the voltage division output from the cylindrical voltage division electrode and calculates the voltage to be measured.

[0052] The performance according to one embodiment of the present invention was measured by comparison with a standard voltage divider at 80%, 100%, and 120% of the rated voltage in accordance with KS C IEC 61869-11 regarding measuring transformers, and an example of the analysis results is shown in [Table 2] below.

[0053]

[0054] Based on the rated voltage (100%), the voltage division ratio error is a maximum of 0.04% (0.12%-0.08%) and the phase error is "0", which is a result that fully satisfies the allowable criteria for the accuracy class 0.2 of the measuring transformer.

[0055] These excellent results are due to the fact that the electrode system was fabricated as a coaxial cylindrical structure and the voltage divider electrode was wrapped with a shielding electrode so as not to be affected by an external electric field.

[0056] When a measuring transformer is installed inside a switchboard, it comes into close proximity to other phases, and to evaluate the impact of this, it is specified in KS C IEC 61869-11. For an accuracy class of 0.2, the allowable value is determined by comparing the value measured with the other phase grounded with the value measured with the rated voltage applied to the other phase; for class 0.2, it must not exceed 0.04%, which is 1 / 5 of the maximum allowable voltage division ratio error of 0.2%, and must not exceed 2 min, which is 1 / 5 of the maximum allowable phase error of 10 min.

[0057] An example of the accuracy analysis results due to different phase interference according to one embodiment of the present invention is shown in the following [Table 3].

[0058]

[0059] The above results sufficiently satisfy the acceptance criteria for accuracy class 0.2, and this result is due to the fact that, as explained earlier, the electrode system was manufactured in a coaxial cylindrical structure and the voltage divider electrode was wrapped with a shielding electrode so as not to be affected by an external electric field.

[0060] The above results are examples of the measurement performance of a lossless measurement transformer according to one embodiment of the present invention, and indicate that the present invention has technology capable of controlling the accuracy of the lossless measurement transformer to class 0.2, class 0.5, and class 1.0.

[0061] As such, the lossless measuring transformer according to one embodiment of the present invention satisfies a maximum accuracy of 0.2 in measuring performance, and is at a level that can sufficiently replace the accuracy of 1.0 of the existing wound-core instrument transformer currently used in switchboards with high accuracy.

[0062] According to one embodiment of the present invention, a lossless measuring transformer is installed in a switchboard to replace a conventional iron core type instrument transformer. Unlike conventional iron core type instrument transformers, the proposed lossless measuring transformer uses a non-contact capacitive voltage divider method and is completely electrically isolated from the primary charging part (in other words, the connection part to which voltage is applied), thereby completely preventing accidents caused by insulation breakdown. Since it does not use an iron core or copper wire, it is possible to miniaturize and lighten it to 1 / 25 the weight and 1 / 8 the volume compared to a conventional iron core type instrument transformer of the same rating, enabling the compactness of the switchboard. Furthermore, since iron loss and copper loss do not occur, it can contribute significantly to preventing electrical safety accidents and carbon neutrality through energy savings in the switchboard.

[0063] More specifically, by applying a non-contact voltage divider method in which the high-voltage conductor and voltage detection electrode are completely separated within the switchgear, it is possible to structurally prevent ground faults, short-circuit accidents, and fires or explosions caused by insulation breakdown—a chronic problem of conventional iron-core instrument transformers—while simultaneously ensuring the overall insulation safety of the switchgear by securing insulation distance through miniaturization and lightweight design.

[0064] FIG. 6 is a diagram illustrating a power fuse for protecting a wound-core type instrument transformer according to the prior art. The lossless measuring transformer of the present invention is non-contact, so the power fuse for protecting the conventional wound-core type instrument transformer of FIG. 6 can be omitted.

[0065] FIG. 7 is a drawing for comparing a switchboard (top) with a wound-core instrument transformer according to the prior art and a switchboard (bottom) with a PT panel omitted when a lossless measuring transformer according to the present invention is applied. The lossless measuring transformer of the present invention is made smaller and lighter with a volume of 23%, an installation cross-sectional area of ​​25%, and a weight of 4% compared to the existing wound-core instrument transformer, so that no separate installation space is required, and as shown in FIG. 7, the PT panel can be omitted from the existing switchboard.

[0066] In addition, as a capacitive voltage divider method that does not use an iron core or coil, there is no iron loss or copper loss, and the no-load loss (standby power) per lossless measuring transformer is drastically reduced to 1 / 15 of the level (7.6VA → 0.5VA) compared to conventional wound-core instrument transformers, thereby reducing reactive power by 180VA to 450VA per extra-high voltage switchgear system. Wound-core instrument transformers are an iron processing industry consisting of more than 90% iron core (silicon steel sheet, amalbus steel, etc.) and copper wire, which generates high carbon emissions during production; however, the measuring transformer of the present invention is an advanced component manufacturing industry that does not use iron or copper metals. This is shown in detail in the following [Table 4].

[0067]

[0068] FIG. 8 is a drawing illustrating the installation restriction regulations for wound-core instrument transformers and shows a single-line diagram of a substation facility. FIG. 9 is a drawing illustrating the installation of a lossless measuring transformer according to the present invention within a switchgear. In existing switchgear, as shown in FIG. 8, it was impossible to install devices for system protection and safety due to regulations and the lack of installation space; however, the lossless measuring transformer of the present invention, as shown in FIG. 9 (a) and (b), replaces the equipment and busbar support insulators, allowing for installation and voltage measurement at any location, thereby ensuring switchgear protection and electric shock safety. For reference, according to the installation restriction regulations for wound-core instrument transformers, a wound-core instrument transformer cannot be installed on the primary side of the instrument transformer (MOF) installed for KEPCO electricity bill notification.

[0069] The secondary voltage of the lossless measuring transformer of the present invention is 1.32V at the primary voltage of 13.2kV, so there is no electric shock accident to the human body even with direct contact. In contrast, the secondary voltage of the conventional wound-core instrument transformer is 110V at all primary rated voltages, so electric shock accidents occur upon contact with the human body and may result in injury or death.

[0070]

[0071] Thus, the lossless measuring transformer of the present invention has a 3-electrode double cylindrical structure. As shown in FIG. 4, the electrode system is coaxially structured so that the voltage divider electrode (420) for detecting voltage is completely blocked by a cylindrical shielding electrode (430), so the structure is not affected at all by external voltage or electric field interference, and stably maintains the voltage division ratio even if the installation environment is different. In addition, the voltage divider electrode (420) and the shielding electrode (430) are also formed with the same insulating material to have the same high-voltage capacitance ( C h ) and low-voltage capacitance( C L A capacitor () with the same temperature coefficient (+) of the relative permittivity and connected to a low-voltage section for adjusting the voltage division ratio C L By applying the principle that the dielectric constant of the dielectric constant of the insulating material has a linear temperature coefficient (-) that is inversely related to the dielectric constant of the insulating material, the difference in the voltage division ratio due to temperature change is completely resolved physically without a separate temperature compensation circuit. Accordingly, the voltage division ratio is maintained stably from -25℃ to +40℃.

[0072] Conventional wound-core instrument transformers generate iron losses (hysteresis loss + eddy current loss) and copper losses in the iron core and copper wires. This is power that is wasted and not used as energy, which is lagging reactive power due to inductance (L). In contrast, lossless measuring transformers based on the principle of capacitive voltage division generate leading reactive power due to capacitance, which is the same power that is wasted and not used as energy as lagging reactive power. When comparing only the no-load loss (absolute value), power loss can be reduced by 85% compared to wound-core instrument transformers per switchgear system, as shown in the following [Table 6].

[0073]

[0074] However, in actual application and operation, the reactive power loss of the load supplied through the switchboard is entirely lagging; to compensate for this and offset the reactive power, power capacitors are installed to compensate for the leading reactive power. Therefore, the leading reactive power generated by the lossless measuring transformer of the present invention is not a loss component, and since it serves to compensate for and offset the lagging reactive power, it can be considered that there is absolutely no loss.

[0075] FIG. 10 is a diagram illustrating power components in a lossless measuring transformer according to an embodiment of the present invention, where FIG. 10 (a) is a vector diagram of power components and FIG. 10 (b) is a vector diagram of apparent power, which is the vector sum of active power and reactive power. As shown in FIG. 10, the actual apparent power is represented as the vector sum of active power and reactive power, and it can be seen that when leading reactive power is supplied, lagging reactive power (loss) is offset and the apparent power is also reduced.

[0076] Conventional wound-core instrument transformers have a secondary output voltage of 110V and a supply current of 100mA or more, posing a risk of electric shock upon contact; however, lossless measuring transformers have a secondary output voltage of 1.32V and a supply current of 1mA or less, posing no risk of electric shock even upon human contact. Domestic industrial safety and health laws stipulate a safety voltage of AC 30V or less.

[0077] While conventional iron-core instrument transformers could not be installed upstream of instrument transformers (MOF) due to regulations (size issues), lossless measuring transformers can be installed anywhere on a switchboard thanks to their compact and lightweight design, identical to support insulators, enabling them to alert of live-line conditions and ensure safety against electric shock.

[0078] Conventional coiled core instrument transformers must be manufactured for each rated voltage (24kV, 13.2kV, 7.2kV, and 3.6kV), but the lossless measuring transformer of the present invention can replace all of the following ratings on a 1:1 basis with a single rating of 24kV.

[0079] In short, the present invention provides a lossless measuring transformer with a 3-electrode double cylindrical structure.

[0080] In one embodiment of the present invention, the lossless measuring transformer comprises a high-voltage round bar electrode (410) for voltage detection, a cylindrical voltage divider electrode (420) arranged to surround the high-voltage round bar electrode (410) and block voltage or electric field interference from another external phase, a polymer insulator (411) for separating the high-voltage round bar electrode (410) and the cylindrical voltage divider electrode, a cylindrical shielding electrode (430) arranged to surround the cylindrical voltage divider electrode (420) and block external voltage or electric field interference, a polymer insulator (411) for separating the cylindrical voltage divider electrode (420) and the cylindrical shielding electrode (430), a capacitor connected between the cylindrical voltage divider electrode (420) and the cylindrical shielding electrode (430), and a matching impedance connected in parallel with the capacitor inserted between the cylindrical voltage divider electrode (420) and ground.R b Includes ).

[0081] In one embodiment of the present invention, the lossless measuring transformer has a capacitance (C) between a high-voltage round bar electrode (410) and a cylindrical voltage divider electrode (420). h The capacitance (C) of the capacitor inserted between the cylindrical voltage divider electrode (420) and ground L The partial pressure ratio is maintained using the negative temperature coefficient of ).

[0082] In one embodiment of the present invention, the lossless measurement transformer has a matching impedance ( R b Using ), the matching impedance ( R b The phase synchronization of the voltage to be measured is adjusted by adding a resistive current.

[0083] In one embodiment of the present invention, the lossless measuring transformer sets the output voltage to 100:1 to 100,000:1 of the primary high voltage.

[0084] In one embodiment of the present invention, the lossless measuring transformer is manufactured with a single rated voltage, allowing for one-to-one replacement of rated voltages lower than the rated voltage.

[0085] In one embodiment of the present invention, the polymer insulating material (411) for separating the high-voltage rod electrode (410) and the cylindrical partial pressure electrode (420) and the polymer insulating material for separating the cylindrical partial pressure electrode (420) and the cylindrical shielding electrode (430) are the same material.

[0086] Meanwhile, the present invention provides a switchboard, which includes a high-voltage busbar and a lossless measuring transformer of a 3-electrode double cylindrical structure configured to measure the voltage of the busbar.

[0087] Meanwhile, the present invention provides a voltage measurement method using a lossless measuring transformer with a 3-electrode double cylindrical structure. This includes the step (step 510) of applying a voltage to be measured to a high-voltage round bar electrode (410), and the capacitance ( formed between the high-voltage round bar electrode (410) and the cylindrical voltage divider electrode (420). C h A step (step 520) of generating a voltage divider voltage at the cylindrical voltage divider electrode (420) by dividing the voltage to be measured by a capacitor connected between the cylindrical voltage divider electrode (420) and the cylindrical shielding electrode (430) and a capacitor inserted between the cylindrical voltage divider electrode (420) and ground, and a matching impedance ( R b It includes a step (step 530) of correcting the phase error of the voltage divider using ), and a step (step 540) of detecting the voltage divider output from the cylindrical voltage divider electrode (420) and calculating the voltage to be measured.

[0088] In one embodiment of the present invention, the step (step 520) of generating a divided voltage is a capacitance between a high-voltage rod electrode (410) and a cylindrical divided voltage electrode (420). C h The capacitance of the capacitor inserted between the cylindrical voltage divider electrode (420) and ground ( C L The partial pressure ratio is maintained using the negative temperature coefficient of ).

[0089] In one embodiment of the present invention, the step of correcting the phase error (step 530) is a matching impedance ( R b Using ), the matching impedance ( R b The phase synchronization of the voltage to be measured is adjusted by adding a resistive current.

[0090] The various embodiments of this document and the terms used therein are not intended to limit the technology described in this document to specific embodiments and should be understood to include various modifications, equivalents, and / or substitutions of such embodiments. In relation to the description of the drawings, similar reference numerals may be used for similar components. A singular expression may include a plural expression unless the context clearly indicates otherwise. In this document, expressions such as "A or B," "at least one of A and / or B," "A, B or C," or "at least one of A, B and / or C" may include all possible combinations of items listed together. Expressions such as "first," "second," "first," or "second" may modify the components, regardless of order or importance, and are used only to distinguish one component from another and do not limit the components. When it is mentioned that a certain (e.g., first) component is "(functionally or telecommunicationally) connected" or "connected" to another (e.g., second) component, said certain component may be directly connected to said other component or connected through another component (e.g., third component).

[0091] According to various embodiments, each of the described components may include a singular or multiple entities. According to various embodiments, one or more of the aforementioned components or steps may be omitted, or one or more other components or steps may be added. Generally or additionally, multiple components may be integrated into a single component. In this case, the integrated component may perform one or more functions of each of the multiple components in the same or similar manner as those performed by the corresponding component among the multiple components prior to integration. According to various embodiments, steps performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the steps may be executed in a different order, omitted, or one or more other steps may be added.

Claims

Claim 1 In a lossless measuring transformer of a 3-electrode double cylindrical structure, the high-voltage round bar electrode for voltage detection; a cylindrical voltage divider electrode arranged to surround the high-voltage round bar electrode and block voltage or electric field interference from another external phase; a polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode; a cylindrical shielding electrode arranged to surround the cylindrical voltage divider electrode and block external voltage or electric field interference; and a polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode. A lossless measuring transformer comprising a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with a capacitor inserted between the cylindrical voltage divider electrode and ground, wherein the lossless measuring transformer maintains the voltage divider ratio using the negative temperature coefficient of the capacitance between the high voltage rod electrode and the cylindrical voltage divider electrode and the capacitance of the capacitor inserted between the cylindrical voltage divider electrode and ground. Claim 2 delete Claim 3 In a lossless measuring transformer of a 3-electrode double cylindrical structure, the high-voltage round bar electrode for voltage detection; a cylindrical voltage divider electrode arranged to surround the high-voltage round bar electrode and block voltage or electric field interference from another external phase; a polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode; a cylindrical shielding electrode arranged to surround the cylindrical voltage divider electrode and block external voltage or electric field interference; and a polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode. A lossless measurement transformer comprising a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with a capacitor inserted between the cylindrical voltage divider electrode and ground, wherein the lossless measurement transformer adjusts the phase synchronization of the voltage to be measured by adding the resistive current of the matching impedance to the capacitive current of the capacitor inserted between the cylindrical voltage divider electrode and ground using the matching impedance. Claim 4 In claim 1, the lossless measuring transformer sets the output voltage to 100:1 to 100,000:1 of the primary high voltage. Claim 5 In claim 1, the lossless measuring transformer is manufactured with a single rated voltage and is capable of replacing a rated voltage lower than or equal to the rated voltage on a one-to-one basis. Claim 6 A lossless measuring transformer according to claim 1, wherein the polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode and the polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode are made of the same material. Claim 7 A switchgear comprises: a high-voltage busbar; and a lossless measuring transformer having a 3-electrode double cylindrical structure configured to measure the voltage of the busbar, wherein the lossless measuring transformer comprises: a high-voltage round bar electrode for voltage detection; a cylindrical voltage divider electrode arranged to surround the high-voltage round bar electrode and block voltage or electric field interference from another external phase; a polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode; a cylindrical shielding electrode arranged to surround the cylindrical voltage divider electrode and block external voltage or electric field interference; and a polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode. A switchboard comprising a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with a capacitor inserted between the cylindrical voltage divider electrode and ground, wherein the lossless measuring transformer maintains the voltage divider ratio using the negative temperature coefficient of the capacitance between the high voltage round bar electrode and the cylindrical voltage divider electrode and the capacitance of the capacitor inserted between the cylindrical voltage divider electrode and ground. Claim 8 delete Claim 9 A switchgear comprises: a high-voltage busbar; and a lossless measuring transformer having a 3-electrode double cylindrical structure configured to measure the voltage of the busbar, wherein the lossless measuring transformer comprises: a high-voltage round bar electrode for voltage detection; a cylindrical voltage divider electrode arranged to surround the high-voltage round bar electrode and block voltage or electric field interference from another external phase; a polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode; a cylindrical shielding electrode arranged to surround the cylindrical voltage divider electrode and block external voltage or electric field interference; and a polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode. A switchboard comprising a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with a capacitor inserted between the cylindrical voltage divider electrode and ground, wherein the lossless measuring transformer adjusts the phase synchronization of the measured voltage by adding the resistive current of the matching impedance to the capacitive current of the capacitor inserted between the cylindrical voltage divider electrode and ground using the matching impedance. Claim 10 A voltage measurement method using a lossless measurement transformer with a 3-electrode double cylindrical structure, wherein the lossless measurement transformer comprises: a high-voltage round bar electrode for voltage detection; a cylindrical voltage divider electrode arranged to surround the high-voltage round bar electrode and block voltage or electric field interference from another external phase; a polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode; a cylindrical shielding electrode arranged to surround the cylindrical voltage divider electrode and block external voltage or electric field interference; and a polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode. The method comprises a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with a capacitor inserted between the cylindrical voltage divider electrode and ground, wherein the voltage measuring method comprises: a step of applying a voltage to be measured to the high-voltage round bar electrode; a step of dividing the voltage to be measured by a capacitance formed between the high-voltage round bar electrode and the cylindrical voltage divider electrode, the capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and the capacitor inserted between the cylindrical voltage divider electrode and ground to generate a voltage divider voltage at the cylindrical voltage divider electrode; and a step of correcting a phase error of the voltage divider voltage using the matching impedance. A voltage measurement method comprising the step of detecting a voltage division voltage output from the cylindrical voltage division electrode and calculating the voltage to be measured, wherein the step of generating the voltage division voltage maintains the voltage division ratio by utilizing the negative temperature coefficient of the capacitance between the high-voltage rod electrode and the cylindrical voltage division electrode and the capacitance of the capacitor inserted between the cylindrical voltage division electrode and the ground. Claim 11 delete Claim 12 A voltage measurement method using a lossless measurement transformer with a 3-electrode double cylindrical structure, wherein the lossless measurement transformer comprises: a high-voltage round bar electrode for voltage detection; a cylindrical voltage divider electrode arranged to surround the high-voltage round bar electrode and block voltage or electric field interference from another external phase; a polymer insulator for separating the high-voltage round bar electrode and the cylindrical voltage divider electrode; a cylindrical shielding electrode arranged to surround the cylindrical voltage divider electrode and block external voltage or electric field interference; and a polymer insulator for separating the cylindrical voltage divider electrode and the cylindrical shielding electrode. The method comprises a capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and a matching impedance connected in parallel with a capacitor inserted between the cylindrical voltage divider electrode and ground, wherein the voltage measuring method comprises: a step of applying a voltage to be measured to the high-voltage round bar electrode; a step of dividing the voltage to be measured by a capacitance formed between the high-voltage round bar electrode and the cylindrical voltage divider electrode, the capacitor connected between the cylindrical voltage divider electrode and the cylindrical shielding electrode, and the capacitor inserted between the cylindrical voltage divider electrode and ground to generate a voltage divider voltage at the cylindrical voltage divider electrode; and a step of correcting a phase error of the voltage divider voltage using the matching impedance. A voltage measurement method comprising the step of detecting a voltage division output from the cylindrical voltage division electrode and calculating the voltage to be measured, wherein the step of correcting the phase error is to adjust the phase synchronization of the voltage to be measured by adding the resistive current of the matching impedance to the capacitive current of the capacitor inserted between the cylindrical voltage division electrode and the ground using the matching impedance.

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