WO2019227826A1 - 一种宽频电压互感器 - Google Patents

一种宽频电压互感器 Download PDF

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Publication number
WO2019227826A1
WO2019227826A1 PCT/CN2018/111058 CN2018111058W WO2019227826A1 WO 2019227826 A1 WO2019227826 A1 WO 2019227826A1 CN 2018111058 W CN2018111058 W CN 2018111058W WO 2019227826 A1 WO2019227826 A1 WO 2019227826A1
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Prior art keywords
voltage
resistance
capacitance
signal acquisition
voltage transformer
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PCT/CN2018/111058
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English (en)
French (fr)
Inventor
董巍
高冲
周建辉
庞辉
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全球能源互联网研究院有限公司
国家电网有限公司
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Priority to EP18920773.1A priority Critical patent/EP3780040B1/en
Publication of WO2019227826A1 publication Critical patent/WO2019227826A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/04—Voltage dividers
    • G01R15/06—Voltage dividers having reactive components, e.g. capacitive transformer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/16—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using capacitive devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase ac
    • H01F38/24—Voltage transformers
    • H01F38/26—Constructions

Definitions

  • the present invention relates to the technical field of power systems, and in particular to a wide-band voltage transformer.
  • the DC voltage transformer is an indispensable main equipment in the DC transmission system, and it plays an important role in energy measurement, power monitoring, and relay signal transmission.
  • DC voltage transformers are composed of a series of resistance voltage dividers. In order to prevent the resistance voltage divider from being affected by various transient overvoltages (including lightning overvoltages), it is usually used in resistance voltage dividers. Connect the shunt capacitor in parallel.
  • the specific schematic diagram of the DC voltage transformer is shown in Figure 1. Depending on the voltage level, the number of stages of the resistor divider and capacitor divider is different. In Figure 1, the lowest stage is called the low-voltage arm, and the upper stages constitute the high-voltage arm.
  • R 2 represents the low-voltage arm resistance
  • C 2 represents the low-voltage arm capacitance
  • R 1 represents the high-voltage arm resistance
  • C 1 represents the high-voltage arm capacitance.
  • R 1 R 11 + R 12 + ... + R 1n
  • C 1 C 11 ⁇ C 12 ⁇ ... ⁇ C 1n .
  • the primary voltage Up acts on the high-voltage arm, and the output voltage Us of the low-voltage arm is used to connect the secondary system.
  • the failure rate of DC voltage transformers is relatively high, and most of the failures are insulation failures.
  • Primary insulation reliability issues include primary structural design defects, resistance-capacitance component selection, and insulation design.
  • the structural design defects of the DC voltage transformer are reflected in the resistance voltage divider composed of resistors R 11 , R 12 , ..., R 1n in series and the capacitors C 11 , C 12 , ..., in order to meet the insulation performance requirements.
  • a voltage equalizing capacitor composed of C 1n connected in series is placed inside a hollow insulator, and the two ends are sealed with flanges.
  • the hollow insulator is filled with insulation medium to meet the insulation requirements.
  • the schematic diagram of the overall structure of the DC voltage transformer is shown in Figure 2.
  • the outer surface of the hollow insulator is in the atmospheric environment, and it is easy to accumulate dirt over time. Especially under the action of a DC electric field, the accumulation speed and degree of this kind of dirt will be more serious than that of an AC electric field.
  • the conductivity of dry pollutants is relatively low.
  • the pollutants collected on the surface of the hollow insulator are dampened and the conductivity is increased.
  • the potential distribution outside the hollow insulator is affected by the degree of contamination and the wet state of the outer surface of the hollow insulator.
  • the electrical conductivity is high, and the voltage drop is small.
  • the electrical conductivity is small, and the voltage drop is high.
  • the resistance-capacitor voltage divider inside the DC voltage transformer is not affected by external pollution, the potential distribution from the upper end to the lower end in the axial direction is relatively uniform.
  • the hollow insulator of the DC voltage transformer adopts a single-branch insulator structure.
  • the insulator consists of a composite material sleeve and two metal flanges at the top and bottom.
  • the composite material has low specific heat and poor heat dissipation performance; the metal flange has large specific heat and good heat dissipation performance.
  • Temperature gradient depending on the voltage level, the temperature difference can reach 50K or 60K or more.
  • the resistance value of the resistance element will change at different temperatures. The greater the temperature change, the larger the resistance value deviation will be, which will cause the voltage divider ratio of the resistance voltage divider to change, which will cause measurement errors and affect the DC voltage measurement accuracy. At the same time, excessive temperature rise will affect the working stability of the resistance and capacitance components inside the DC voltage transformer, which will greatly reduce the component life or even permanently damage it.
  • Existing DC voltage transformers allow a maximum ambient temperature of 40 ° C.
  • the circuit topology of the existing DC voltage transformer is to form a resistance-capacitance parallel unit by connecting the resistance element R1 and the capacitor element C1n of each stage of the high-voltage arm in parallel. Primary body of the device.
  • This topology is referred to herein as a resistance-capacitance parallel topology.
  • DC voltage transformers with resistance-capacitance parallel topology can measure DC voltage and low-frequency AC voltage signals (within 3kHz), but cannot measure high-frequency voltage signals.
  • Capacitive voltage transformers used in AC grids reduce the effect of stray capacitance on measurement accuracy by significantly increasing the capacitance.
  • the capacitance should not be allowed to be too large, resulting in low measurement accuracy of low-frequency voltage signals (the error can reach 30%) and cannot It is used for accurate measurement of low-frequency voltage signals in DC grids, and it cannot be applied to voltage measurement and protection of AC grids.
  • the voltage signal output from the low-voltage arm of the existing DC voltage transformer is transmitted to the control room through a cable, and the distance between the control room and the DC voltage transformer can reach hundreds of meters. There is also stray capacitance between the cable and the ground or surrounding grounding body. The longer the cable distance is, the larger the stray capacitance is, which makes the voltage measurement error larger.
  • the embodiments of the present invention are expected to provide a wideband voltage transformer to solve the problems of low insulation reliability, low voltage measurement accuracy, and inability to achieve accurate measurement of wideband voltage signals at least once.
  • An embodiment of the present invention provides a wide-band voltage transformer, including: a hollow insulator, a metal flange, a fixed flange, a resistance-capacitance equalizing component, a resistance-capacitance mixed voltage divider, a base, and a signal acquisition module;
  • Metal flanges are installed at both ends of the hollow insulator; the metal flange at the top of the hollow insulator is connected to the primary system, and the metal flange at the bottom of the hollow insulator is connected to the base;
  • a fixed flange is installed on the inner wall of the metal flange, and two ends of the resistance-capacitance equalizing component are respectively connected to the fixed flange;
  • the top of the resistance-capacitance mixed voltage divider is connected to the primary system, and the bottom of the resistance-capacitance mixed voltage divider is connected to the signal acquisition module.
  • the resistance-capacitance voltage-balancing component includes n resistance-capacitance voltage-balancing units, and the resistance-capacitance voltage-balancing unit includes a parallel voltage-balancing resistor element and a voltage-balancing capacitor element, where n is a positive integer.
  • the resistance-capacitance voltage equalizing component and the resistance-capacitance mixed voltage divider are sealed inside the hollow insulator through a seal ring located on an end face of the metal flange.
  • the resistance-capacitance hybrid voltage divider and the resistance-capacitance equalizing component and the resistance-capacitance hybrid voltage divider and the fixed flange are filled with an insulating medium, and the insulating medium is an insulating oil or Insulation gas.
  • the number of the hollow insulators is determined by the requirements of the working voltage level.
  • a resistance-capacitance voltage equalization component is provided inside each hollow insulator;
  • two or more resistance-capacitance voltage equalization components are arranged inside each hollow insulator, and the resistance-capacitance voltage equalization components are connected in parallel to the fixed flange. between.
  • one or at least two hollow insulators are provided.
  • the number of the hollow insulators is at least two, at least two hollow insulators are connected in series in sequence, metal flanges are installed at both ends of each hollow insulator, and the two ends of the resistance-capacity equalizing component are respectively fixed with the fixing method.
  • One end of the resistance-capacitance hybrid voltage divider is connected to the primary system through a metal flange at the top of the first hollow insulator, and the other end of the resistance-capacitance hybrid voltage divider is connected to the primary system through a metal flange at the bottom of the last hollow insulator.
  • the signal acquisition module is connected as described above.
  • the signal acquisition module includes a chassis and a secondary voltage dividing unit, a signal acquisition unit, and a power supply unit located inside the chassis;
  • An input terminal of the secondary voltage dividing unit is connected to a bottom end of the resistance-capacitance mixed voltage divider, an output terminal of the secondary voltage dividing unit is connected to an input terminal of the signal acquisition unit, and the signal acquisition unit The output end is connected to the control station of the converter station through optical fiber;
  • One end of the power supply unit is connected to the power supply end of the signal acquisition unit, and the other end of the power supply unit is connected to a power supply for a converter station.
  • the resistance-capacitance mixed voltage divider and the secondary voltage-dividing unit each include a plurality of resistance-capacitance mixed voltage-connection units connected in series in sequence;
  • the resistance-capacitance hybrid connection unit includes a measurement capacitance element, a damping resistance element, and a measurement resistance element. After the measurement capacitance element is connected in series with the damping resistance element, it is connected in parallel with the measurement resistance element.
  • one or at least two secondary voltage dividing units are provided.
  • the at least two secondary voltage division units are connected in parallel, and the input terminal of each secondary voltage division unit is connected to the bottom of the resistance-capacitance mixed voltage divider.
  • the terminals are connected, and the output of each secondary voltage division unit is connected to the input of the signal acquisition unit.
  • the signal acquisition unit includes one or at least two signal collectors.
  • the signal acquisition unit when the signal acquisition unit includes at least two signal collectors, at least two signal collectors are connected in parallel, and the input end of each signal collector is connected to a secondary voltage dividing unit. The output is connected to the control room of the converter station.
  • the power supply unit includes one or at least two.
  • each power supply unit when there are at least two power supply units, each power supply unit supplies power to each signal collector.
  • the signal acquisition unit and the base adopt an integrated design, and they are arranged inside the base or close to the base.
  • a voltage range input by the input terminal of the signal acquisition unit is at least three times its rated input signal.
  • the broadband voltage transformer provided by the embodiment of the present invention includes a hollow insulator, a metal flange, a fixed flange, a resistance-capacitance equalizing component, and a resistance-capacitance mixed voltage divider.
  • a metal flange is installed at both ends of the hollow insulator, and the inner wall of the metal flange is provided.
  • Install the fixed flange, the two ends of the resistance-capacitance equalizing component are respectively connected with the fixed flange; the two ends of the resistance-capacitance mixed voltage divider are connected to the primary system and the secondary system through metal flanges respectively, and the wide-band voltage transformer has reliable primary insulation.
  • High performance, high voltage measurement accuracy can achieve accurate measurement of wideband voltage signals;
  • the number of metal flanges is increased by 2N-2 (N is the number of hollow insulators) compared with the prior art.
  • N is the number of hollow insulators
  • the specific heat of the metal flange material is much larger than that of the hollow insulator material.
  • the increase in the number of hollow insulators is conducive to rapid heat dissipation, reducing the internal temperature rise of the voltage transformer, reducing the resistance value offset of the resistor, and improving the DC voltage measurement accuracy. Expand the operating temperature range of voltage transformer products (-40 ° C to + 70 ° C) and improve the operational reliability of wideband voltage transformers;
  • the embodiment of the present invention not only has the measurement capability of DC voltage, low frequency voltage signal, and high frequency voltage signal, but also significantly reduces the resistance value offset of the resistance, the measurement bandwidth can reach more than 2MHz, and the DC voltage measurement accuracy can reach 0.1 level. Time is less than 25us;
  • the embodiments of the present invention significantly reduce the internal temperature rise, and the temperature rise is reduced by more than 50% compared with the DC voltage transformer in the prior art;
  • the ambient temperature range of the wideband voltage transformer provided by the embodiment of the present invention is wider to -40 ° C to + 70 ° C;
  • the embodiment of the present invention significantly reduces the potential difference between the radial (horizontal) hollow insulator and the resistance-capacitor voltage divider, improves the local electric field distribution of the hollow insulator, and effectively avoids flashover on the outside of the hollow insulator, and the hollow insulator and internal resistance.
  • a breakdown failure occurs between the capacitor-to-capacitor voltage divider and the resistance-capacitance voltage equalization component, which significantly improves the pollution tolerance level of the wideband voltage transformer and improves the reliability of the primary insulation.
  • the resistance-capacitance mixed voltage divider in the embodiment of the present invention is in a perfect shielding state, minimizes additional errors, and improves the measurement accuracy of the DC voltage and the measurement accuracy of the wideband voltage signal;
  • the embodiment of the present invention integrates the design of the secondary signal acquisition unit and the voltage transformer, converts the electrical signal into an optical signal on the spot, and transmits the optical signal to the control station of the converter station through the optical cable.
  • the optical signal is not affected by stray capacitance. , To further ensure the high measurement accuracy of wideband voltage transformers;
  • the number of secondary voltage dividing units is increased.
  • a plurality of secondary voltage dividing units are connected in parallel, and one end is connected to a low-voltage arm of a resistance-capacitance mixed voltage divider, and the other end is connected to a signal acquisition unit;
  • the number of signal acquisition units in the embodiment of the present invention is the same as the number of secondary voltage division units, and they are connected one by one. Each signal acquisition unit is independently powered and works independently. Any one of the secondary voltage division units or signal acquisition units fails or is damaged. , Does not affect the normal transmission of other signals, ensuring the reliability of the operation of the wideband voltage transformer;
  • the wide-band voltage transformer provided by the embodiment of the present invention is applicable to both an AC system and a DC system;
  • the embodiments of the present invention have a wide range of applications, and the specific application ranges include DC power transmission projects, AC power transmission / distribution projects, high-speed railway power grids, and any field and occasion with a wide-band voltage signal measurement requirement.
  • FIG. 1 is a schematic diagram of a DC voltage transformer in the prior art
  • FIG. 2 is a schematic diagram of the overall structure of a DC voltage transformer in the prior art
  • FIG. 3 is a structural diagram of a resistance-capacitance mixed voltage divider in an embodiment of the present invention.
  • FIG. 4 is a structural diagram of a resistance-capacitance voltage-balancing component according to an embodiment of the present invention.
  • FIG. 5 is a structural diagram of a wide-band voltage transformer in an embodiment of the present invention.
  • FIG. 6 is a structural diagram of a signal acquisition module in an embodiment of the present invention.
  • FIG. 5 An embodiment of the present invention provides a wide-band voltage transformer.
  • the specific structural diagram is shown in FIG. 5, which includes a hollow insulator 2, a metal flange 1, a fixed flange 4, a resistance-capacitance voltage equalizing component 3, and a resistance-capacitance hybrid coupling.
  • the metal insulator 1 is installed at both ends of the hollow insulator 2; the metal flange at the top of the hollow insulator 2 is connected to the primary system; the metal flange at the bottom of the hollow insulator 2 is connected to the base 7; The two ends of the resistance-capacitance pressure equalization component 3 are respectively connected to the fixed flange 4; the two ends of the resistance-capacitance mixed voltage divider 5 are connected to the primary system and the signal acquisition module 8 through the metal flange 1 respectively.
  • the signal acquisition module 8 and the base 7 are integrally designed and installed at the bottom of the wideband voltage transformer.
  • the above-mentioned hollow insulator 2 may be provided with one or at least two, as follows:
  • metal flanges 1 (a total of 2 metal flanges) are installed at both ends of the hollow insulator 2 and a fixed flange 4 is installed on the inner wall of the metal flange 1 (that is, 2 fixing methods are provided).
  • Blue 4 the two ends of the resistance-capacitance equalizing component 3 are respectively connected to the fixed flange 4, and the two ends of the resistance-capacitance mixed voltage divider 5 are respectively connected to the primary system and the signal acquisition module 8 through two metal flanges 1;
  • hollow insulators 2 When the number of hollow insulators 2 is at least two, at least two hollow insulators are connected in series in sequence, metal flanges 1 are installed at both ends of each hollow insulator, fixed flanges 4 are installed on the inner wall of the metal flange 1, and the resistance-capacity equalizing component is installed. Both ends of 3 are connected to the fixed flange 4 respectively.
  • one end of the resistance-capacitance mixed voltage divider 5 is connected to the primary system through the metal flange 1 on the top of the first hollow insulator, and the other end is connected to the metal flange on the bottom of the last hollow insulator. 1 is connected to the signal acquisition module 8.
  • the resistance-capacitance equalizing component 3 and the resistance-capacitance mixed voltage divider 5 are sealed inside the hollow insulator 2 through a seal ring located on an end surface of the metal flange 1.
  • the specific number of the hollow insulators 2 is determined by the requirements of the working condition voltage level, between the resistance-capacitance mixed voltage divider 5 and the resistance-capacitance voltage equalization component 3 and the resistance-capacitance mixed voltage-dividing device.
  • the insulation medium 6 is filled between the device 5 and the fixed flange 4 to maintain good insulation between the resistance-capacitance mixed voltage divider 5 and the resistance-capacitance voltage equalization component 3 and the fixed flange 4.
  • the insulating medium 6 may be an insulating oil or an insulating gas.
  • the number of the resistance-capacitance equalizing components 3 provided inside the hollow insulator 2 is specifically divided into the following two cases:
  • each hollow insulator 2 is provided with a resistance-capacitance voltage equalizing component 3;
  • the measurement accuracy of the wideband voltage transformer is 0.2, which means that the voltage error of the wideband voltage transformer is plus or minus 0.2%.
  • the structural diagram of the resistance-capacitance mixed voltage divider 5 is shown in FIG. 3.
  • the lowermost stage is called a low-voltage arm, and the upper stages constitute a high-voltage arm.
  • the low-voltage arm includes R 2 , C 2, and R 4
  • the high-voltage arm specifically includes R 1 , C 1, and R 3 , where R 1 includes measuring resistance elements R 11 , R 12 , ..., R 1M
  • C 1 includes The capacitance-capacitance elements C 11 , C 12 ,..., C 1M , where R 3 includes damping resistance elements R 31 , R 32 ,..., R 3M .
  • R1 R 11 + R 12 + ...
  • the primary voltage Up acts on the high-voltage arm, and the output voltage Us of the low-voltage arm is used to connect the signal acquisition module 8.
  • the resistance-capacitance mixed voltage divider 5 includes M resistance-capacitance mixed-connection units connected in series, and the resistance-capacitance mixed-connection unit includes a measurement capacitance element, a damping resistance element, and a measurement resistance element. After the measurement capacitance element and the damping resistance element are connected in series, Connect in parallel with the measuring resistance element.
  • the structural diagram of the resistance-capacitance voltage-balancing component 3 is shown in FIG. 4.
  • C 31 , C 32 , ..., C 3n are voltage-capacitance capacitive elements
  • R 51 , R 52 , ..., R 5n are voltage- sharing capacitive elements
  • the resistance-capacitance voltage-balancing component 3 includes n resistance-capacitance voltage-sharing units.
  • the resistance-capacitance voltage-sharing unit includes parallel voltage-sharing resistance elements and voltage-sharing capacitance elements.
  • the signal acquisition module includes a chassis and a secondary voltage division unit, a signal acquisition unit, and a power supply unit located inside the chassis.
  • the input terminal of the secondary voltage division unit Connected to the bottom of the resistance-capacitance mixed voltage divider, the output of the secondary voltage division unit is connected to the input of the signal acquisition unit, and the output of the signal acquisition unit is connected to the control station of the converter station through optical fiber;
  • the number of power supply units is equal to the number of signal acquisition units, that is, each power supply unit independently supplies power to the corresponding signal acquisition unit.
  • the resistance-capacitance mixed voltage divider and the secondary voltage divider unit each include a plurality of resistance-capacitance mixed voltage-connection units connected in series.
  • the resistance-capacitance hybrid unit includes a measurement capacitance element, a damping resistance element, and a measurement resistance element, wherein the measurement capacitance element is connected in series with the damping resistance element and is connected in parallel with the measurement resistance element.
  • the above-mentioned secondary voltage dividing unit is provided with one or at least two, each secondary voltage dividing unit is independently designed, and any one or more secondary voltage dividing units are damaged or abnormal, Does not affect the normal operation of other secondary voltage division units.
  • At least two secondary voltage-dividing units when there are at least two secondary voltage-dividing units, at least two secondary voltage-dividing units are connected in parallel, and the input terminal of each secondary voltage-dividing unit is connected to the resistance-capacitance mixed-connected branch.
  • the bottom of the voltage regulator is connected, and the output of each secondary voltage dividing unit is connected to the input of the signal acquisition unit.
  • the above-mentioned signal acquisition unit includes one or at least two signal collectors, and each signal collector is independently powered, and the signal output of each signal collector does not affect each other.
  • the signal acquisition unit includes at least two signal acquisition units
  • at least two signal acquisition units are connected in parallel, and an input end of each signal acquisition unit is connected to a secondary voltage dividing unit
  • the output of each signal collector is connected to the control room of the converter station.
  • the power supply unit includes one or at least two, and if there are at least two power supply units, each power supply unit supplies power to each signal collector.
  • the power supply units work independently of each other and are routed independently, and each power supply does not interfere with each other. Any damage or abnormality of the power module unit will not affect the normal operation of other power units.
  • the signal acquisition unit and the base adopt an integrated design, and are arranged inside the base 7 or close to the base 7.
  • the input voltage range of the input terminal of the signal acquisition unit is at least 3 times of its rated input signal.
  • the broadband voltage transformer with high accuracy, fast response, high reliability, and field-free inspection provided by the embodiments of the present invention is mainly based on the following three technologies:
  • the present invention proposes a resistance-capacitance mixed voltage divider 5 as shown in FIG. 3.
  • the resistance-capacitance mixed voltage divider 5 includes M resistances connected in series in series.
  • the capacitance-capacitance hybrid unit includes a measurement capacitance element, a damping resistance element, and a measurement resistance element. After the measurement capacitance element is connected in series with the damping resistance element, it is connected in parallel with the measurement resistance element.
  • the voltage transformer using resistance-capacitance hybrid voltage divider 5 has the measurement capability for DC voltage, low-frequency AC voltage, and high-frequency voltage signals, and achieves wide-band and fast measurement of voltage signals.
  • the measurement bandwidth can reach more than 2MHz and the response time Less than 25us, which broadens the application fields and applications of voltage transformers (can be applied to traditional DC transmission projects, flexible DC transmission projects, AC transmission / distribution projects, high-speed railway power grids, and any field and occasion with wide-band voltage signal measurement requirements) .
  • a multi-stage cascaded resistance-capacitor voltage equalization component 3 is used.
  • the resistance-capacitance voltage equalization component 3 includes n (n is a positive integer) resistance-capacitance voltage equalization units, and the resistance-capacitance voltage equalization unit includes parallel voltage equalization resistors. Components and grading capacitor components.
  • Multi-section series hollow insulators are used instead of the existing single-core hollow insulators. Each section of the hollow insulator is installed in parallel with a resistance-capacitance voltage equalizing unit. Both ends of the resistance-capacitance voltage equalizing unit are respectively connected to the fixed flanges 4 at the ends of the corresponding hollow insulator.
  • the resistance-capacitance voltage equalization units connected in parallel to the hollow insulators of each section are also connected in series from top to bottom, and are sealed together with the resistance-capacitance mixed voltage divider 5 in the hollow insulator.
  • the resistance-capacitance voltage equalization unit is not electrically connected to the resistance-capacitance mixed voltage divider 5 in the same hollow insulator. Since the resistance-capacitance voltage equalizing component 3 is packaged inside the hollow insulator and is not affected by the external pollution environment, the resistance element placed inside it can clamp the axial (vertical) DC potential of each section of the hollow insulator, so that the hollow insulator Has a relatively uniform potential distribution in the axial direction.
  • the potential difference between the hollow insulator and the resistance-capacitance mixed voltage divider 5 in the radial direction (horizontal direction) is effectively reduced, thereby improving the local electric field distribution of the hollow insulator, effectively Avoid flashover on the outside of hollow insulators and breakdown failures between hollow insulators and internal resistance-capacitor voltage dividers and resistance-capacitance grading capacitors, which significantly improves the level of contamination tolerance of wide-band voltage transformer products.
  • the embodiment of the present invention adopts a multi-level cascade technology, and a plurality of shorter hollow insulators are used to replace a single longer hollow insulator, and the number of metal flanges is increased by 2N-2 compared with the prior art (N represents the number of hollow insulators) ), There are 2N metal flanges.
  • N represents the number of hollow insulators
  • the specific heat of the metal flange material is much larger than that of the hollow insulator material.
  • the increase in the number of hollow insulators is conducive to rapid heat dissipation, reducing the internal temperature rise of the voltage transformer, reducing the resistance value offset of the resistor, and improving the DC voltage measurement accuracy. Widen the operating temperature range of voltage transformer products (-40 ° C to + 70 ° C) to improve the operational reliability of wideband voltage transformers.
  • a stray capacitance exists between the high-voltage arm of the DC voltage transformer and the surrounding grounded or charged body. Under the action of low-frequency and high-frequency AC voltage, the stray capacitance current flows out or flows into the high-voltage arm, causing a voltage measurement error. This error is called additional error, and the additional error increases as the voltage level increases.
  • the embodiment of the present invention adopts a multi-stage cascaded resistance-capacitance voltage equalization component 3, and a resistance-capacitance voltage-balanced component 3 is connected in parallel at both ends of each hollow insulator.
  • the function of the voltage equalizing resistance element is to make the axial potential of the hollow insulator of the voltage transformer uniformly distributed.
  • the role of the voltage equalizing capacitor element is twofold: 1 Prevent the voltage equalizing resistor element from being damaged by various transient overvoltages (including lightning overvoltage); 2 Use the voltage equalizing capacitor element to block the resistance Capacitive divider component current flowing in or out through stray capacitance.
  • the capacitance current to ground and the leakage current on the surface of the hollow insulator are provided by the resistance-capacitance equalizing component 3 without passing through the resistance-capacitance hybrid voltage divider 5, so that the resistance-capacitance hybrid voltage divider 5 is in a perfect shielding state to the maximum extent. Reduce additional errors and ensure high accuracy of low-frequency and high-frequency AC voltage signal measurement.
  • the embodiment of the present invention integrates a signal acquisition unit and a voltage transformer, and converts an electric signal of an existing voltage transformer into an optical signal on a low-voltage side, and transmits the optical signal to a control room for a long distance through an optical cable.
  • This technology completely solves the problem of additional error interference caused by stray capacitance interference when the electrical signal is transmitted through the cable, further reduces the additional error and improves the measurement accuracy of the voltage signal.

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  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
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Abstract

本发明实施例公开了一种宽频电压互感器，包括：空心绝缘子、金属法兰、固定法兰、阻容均压组件、阻容混联分压器、底座和信号采集模块；空心绝缘子两端安装金属法兰，空心绝缘子顶端的金属法兰与一次系统连接，空心绝缘子底端的金属法兰与底座连接；金属法兰的内壁安装固定法兰，阻容均压组件两端分别与固定法兰连接；阻容混联分压器顶端与一次系统连接，阻容混联分压器底端与信号采集模块连接。

Description

一种宽频电压互感器
相关申请的交叉引用
本申请基于申请号为201810549899.0、申请日为2018年05月31日的中国专利申请提出，并要求该中国专利申请的优先权，该中国专利申请的全部内容在此以引入方式并入本申请。
技术领域
本发明涉及电力系统技术领域，具体涉及一种宽频电压互感器。
背景技术
直流输电系统中直流电压互感器是不可缺少的主设备，承担着电能计量、电量监测、继保信号传送等的重要作用。目前，直流电压互感器是由一系列电阻元件串联而成的电阻分压器构成，为了防止电阻分压器受各种暂态过电压(包括雷电过电压)的影响，通常在电阻分压器上并联均压电容器。具体的直流电压互感器原理图如图1所示。根据电压等级的不同，组成的电阻分压器和电容分压器级数不同。图1中，最下端的一级称之为低压臂，之上若干级构成高压臂，R 2表示低压臂电阻，C 2表示低压臂电容，R 1表示高压臂电阻，C 1表示高压臂电容，其中R 1＝R 11+R 12+...+R 1n，C 1＝C 11∥C 12∥...∥C 1n。一次电压Up作用于高压臂，低压臂输出电压Us用于连接二次系统。
上述直流电压互感器具有如下三方面的缺点：
1)结构设计缺陷导致一次绝缘可靠性低：
在直流输电工程的一次设备中，直流电压互感器故障率比较高，故障以绝缘故障居多。一次绝缘可靠性问题主要包括一次结构设计缺陷、阻容 元件选型和绝缘设计等。
直流电压互感器的结构设计缺陷体现在为了满足绝缘性能要求，由电阻R 11、R 12、...、R 1n串联构成的电阻分压器及由电容C 11、C 12、...、C 1n串联构成的均压电容器被安置在一支空心绝缘子内部，两端用法兰封装。空心绝缘子内部充满绝缘介质以满足绝缘要求，直流电压互感器整体结构示意图如图2。空心绝缘子外表面处于大气环境下，日积月累容易聚集污物，特别是在直流电场作用下，这种污物的聚集速度和程度会比交流电场更严重。干燥的污秽物电导率比较低，遇上大雾或小雨前期，空心绝缘子表面聚集的污秽物受潮，电导率增大。这种情况，空心绝缘子外侧的电位分布受空心绝缘子外表面污秽程度及潮湿状态影响，湿度较大的区域，电导率高，电压降小；湿度较小的区域，电导率小，电压降高。于此同时，直流电压互感器内部的阻容分压器由于不受外界污秽的影响，轴向上从上端到下端的电位分布呈现比较均匀的状态。污秽的影响导致直流电压互感器轴向及径向电位分布极不均匀，使局部产生较大电位差，而电位分布不均将直接影响局部电场强度，使电场强度分布发生畸变，当这种畸变严重到足以游离空气的时候，空心绝缘子外侧就会发生闪络现象(即污秽闪络现象)，严重时会导致空心绝缘子与内部阻容元件间发生击穿故障，使直流电压互感器出现永久性损坏。
2)轴向温度梯度大且温升高，导致直流电压测量精度低：
直流电压互感器空心绝缘子采用单支绝缘子结构，绝缘子由复合材料套管和位于顶部与底部的两个金属法兰组成。复合材料比热小，散热性能差；金属法兰比热大，散热性能好。意味着现有结构的直流电压互感器散热性能差，导致发热元件(即电阻)产生的热量随着绝缘介质汇集到空心绝缘子内部的上端，使得直流电压互感器空心绝缘子内部上端和下端出现较大的温度梯度，视电压等级的不同，温差可达50K或60K以上。电阻元 件在不同温度下其阻值将发生改变，温度变化越大，阻值偏移越大，进而使电阻分压器的分压比发生变化，带来测量误差，影响直流电压测量精度。同时，过高的温升将对直流电压互感器内部的电阻及电容元件的工作稳定性产生影响，使元件寿命大大减少甚至永久损坏。现有直流电压互感器允许最高环境温度为40℃。
3)无法实现对于宽频电压信号的准确测量，具体体现在：
3-1)不具备高频电压信号(3kHz-200kHz以上)的测量能力：
现有的直流电压互感器的电路拓扑结构是将高压臂每级电阻元件R1与电容元件C1n并联组成若干阻容并联单元，随后将阻容并联单元串联组成阻容分压器，构成直流电压互感器的一次本体。在此将该拓扑结构称为阻容并联拓扑结构。采用阻容并联拓扑结构的直流电压互感器可以对直流电压、低频交流电压信号(3kHz以内)进行测量，但是无法测量高频电压信号。
为实现柔性直流电网的超高速保护，相对于常规直流工程，柔性直流电网系统需要电压、电流互感器具有200kHz以上的截止频率，25us以下的响应时间。电压变化率和幅值的准确测量对于柔性直流电网实现快速、可靠、准确保护至关重要。宽测量范围、快速传变特性、低延迟时间的电压互感器能够对系统额定参数和故障参数进行宽范围测量，并具有较为准确测量精度，较低的延迟特性，能够准确测量到发生故障后的行波过程。根据国家标准(GB/T 26217-2010)，直流电压互感器截至频率(-3dB)仅为3kHz，响应时间250us。上述对于频率特性的要求已无法满足柔性直流电网快速保护的要求。
3-1)低频电压信号(0Hz-3kHz)的测量精度低：
由于直流电压互感器高压臂与周围的接地体或带电体之间存在杂散电容，在高电压作用下，杂散电容电流流出或流入高压臂，导致电压测量误 差。这种误差称为附加误差，附加误差随着电压等级的增高而加大。
交流电网中使用的电容式电压互感器通过显著增大电容量的措施来减少杂散电容对于测量精度的影响。但对于直流电压互感器，由于其原理与交流电压互感器不同，电气性能要求也不同，因此电容量不允许取值过大，导致低频电压信号的测量精度低(误差可达30％)，无法用于直流电网中低频电压信号的准确测量，更无法应用于交流电网的电压计量与保护。
现有直流电压互感器低压臂输出的电压信号通过电缆传输至控制室，控制室与直流电压互感器的距离可达数百米。电缆与大地或周围接地体之间也存在杂散电容，电缆距离越长杂散电容越大，从而使电压测量误差越大。
发明内容
本发明实施例期望提供一种宽频电压互感器，以至少解决一次绝缘可靠性低、电压测量精度低以及无法实现宽频电压信号的准确测量的不足的问题。
为了实现上述发明目的，本发明实施例采取如下技术方案：
本发明实施例提供了一种宽频电压互感器，包括：空心绝缘子、金属法兰、固定法兰、阻容均压组件、阻容混联分压器、底座和信号采集模块；
所述空心绝缘子两端安装金属法兰；所述空心绝缘子顶端的金属法兰与一次系统连接，所述空心绝缘子底端的金属法兰与所述底座连接；
所述金属法兰的内壁安装固定法兰，所述阻容均压组件两端分别与所述固定法兰连接；
所述阻容混联分压器顶端与所述一次系统连接，所述阻容混联分压器底端与所述信号采集模块连接。
在一实施例中，所述阻容均压组件包括n个阻容均压单元，所述阻容均压单元包括并联的均压电阻元件和均压电容元件；其中，n为正整数。
在一实施例中，所述阻容均压组件与所述阻容混联分压器通过位于金属法兰端面的密封圈密封于空心绝缘子内部。
在一实施例中，所述阻容混联分压器与阻容均压组件之间以及阻容混联分压器与固定法兰之间均充满绝缘介质，所述绝缘介质采用绝缘油或绝缘气体。
在一实施例中，所述空心绝缘子的数量由工况电压等级要求确定。
在一实施例中，若实际工况要求宽频电压互感器测量精度为0.2级，则每个空心绝缘子内部设置1个阻容均压组件；
若实际工况要求所述宽频电压互感器测量精度高于0.2级，则在每个空心绝缘子内部设置2个或2个以上阻容均压组件，所述阻容均压组件并联于固定法兰之间。
在一实施例中，所述空心绝缘子设有一个或至少两个。
在一实施例中，所述空心绝缘子的数量为至少两个时，至少两个空心绝缘子依次串联，每个空心绝缘子两端安装金属法兰，所述阻容均压组件两端分别与固定法兰连接；
所述阻容混联分压器一端通过第一个空心绝缘子顶端的金属法兰与一次系统连接，所述阻容混联分压器的另一端通过最后一个空心绝缘子底端的金属法兰与所述信号采集模块连接。
在一实施例中，所述信号采集模块包括机箱以及位于机箱内部的二次分压单元、信号采集单元和电源单元；
所述二次分压单元的输入端与所述阻容混联分压器底端连接，所述二次分压单元的输出端与所述信号采集单元的输入端连接，所述信号采集单元的输出端通过光纤与换流站控制室连接；
所述电源单元一端与所述信号采集单元的电源端连接，所述电源单元另一端与换流站用电源连接。
在一实施例中，所述阻容混联分压器和二次分压单元均包括多个依次串联的阻容混联单元；
所述阻容混联单元包括测量电容元件、阻尼电阻元件和测量电阻元件，所述测量电容元件与阻尼电阻元件串联后，与测量电阻元件并联。
在一实施例中，所述二次分压单元设有一个或至少两个。
在一实施例中，所述二次分压单元为至少两个时，所述至少两个二次分压单元并联，每个二次分压单元的输入端与阻容混联分压器底端连接，每个二次分压单元的输出端与信号采集单元的输入端连接。
在一实施例中，所述信号采集单元包括一个或至少两个信号采集器。
在一实施例中，所述信号采集单元包括至少两个信号采集器时，至少两个信号采集器并联，每个信号采集器的输入端与二次分压单元连接，每个信号采集器的输出端与换流站控制室连接。
在一实施例中，所述电源单元包括一个或至少两个。
在一实施例中，所述电源单元为至少两个时，每个电源单元为每个信号采集器供电。
在一实施例中，所述信号采集单元与底座采用一体化设计，且其布置于所述底座内部或紧靠所述底座。
在一实施例中，所述信号采集单元输入端输入的电压范围为其额定输入信号的至少3倍。
本发明实施例提供的宽频电压互感器包括空心绝缘子、金属法兰、固定法兰、阻容均压组件、阻容混联分压器，空心绝缘子两端安装金属法兰，金属法兰的内壁安装固定法兰，阻容均压组件两端分别与固定法兰连接；阻容混联分压器两端分别通过金属法兰与一次系统和二次系统连接，该宽频电压互感器一次绝缘可靠性高，电压测量精度高，能够实现宽频电压信号的准确测量；
本发明实施例中金属法兰数量较现有技术增加了2N-2个(N代表空心绝缘子数量)，空心绝缘子数量越多，金属法兰的数量则越多。金属法兰材料的比热远远大于空心绝缘子材料，空心绝缘子数量的增多有利于迅速散热，降低电压互感器内部温升，减小了电阻的阻值偏移，提高了直流电压测量精度，显著拓宽电压互感器产品使用温度范围(-40℃至+70℃)，提高宽频电压互感器的运行可靠性；
本发明实施例不仅具有直流电压、低频电压信号、高频电压信号的测量能力，且显著减小了电阻的阻值偏移，测量带宽可达2MHz以上，直流电压测量精度可达0.1级，响应时间小于25us；
本发明实施例显著降低了自身内部温升，与现有技术中的直流电压互感器相比，温升降低了50％以上；
本发明实施例提供的宽频电压互感器使用环境温度范围与现有技术中的直流电压互感器相比，拓宽至-40℃至+70℃；
本发明实施例显著减小了径向(水平方向)空心绝缘子与阻容分压器的电位差，改善了空心绝缘子局部的电场分布，有效避免空心绝缘子外侧发生闪络，以及空心绝缘子与内部阻容混联分压器、阻容均压组件间发生击穿故障，显著提高了宽频电压互感器污秽耐受等级，提高了一次绝缘可靠性；
本发明实施例中的阻容混联分压器处于完善的屏蔽状态，最大程度减小附加误差，提高了直流电压测量精度和宽频电压信号的测量精度；
本发明实施例将二次信号采集单元与电压互感器一体化设计，就地将电信号转变为光信号，再将光信号通过光缆传输至换流站控制室，光信号不受杂散电容影响，进一步保证了宽频电压互感器的高测量精度；
本发明实施例增加了二次分压单元的数量，多个二次分压单元并联，一端均与阻容混联分压器低压臂连接，另一端均连接信号采集单元；
本发明实施例的信号采集单元数量与二次分压单元数量一致，并一一对应连接，各路信号采集单元独立供电，独立工作，任何一路二次分压单元或信号采集单元发生故障或损坏，均不影响其他路信号的正常传输，保证了宽频电压互感器的运行可靠性；
本发明实施例提供的宽频电压互感器既适用于交流系统，也可以适用于直流系统；
本发明实施例应用范围广，具体应用范围涵盖直流输电工程、交流输/配电工程、高速铁路电网及任何具有宽频电压信号测量需求的领域和场合。
附图说明
图1是现有技术中直流电压互感器原理示意图；
图2是现有技术中直流电压互感器整体结构示意图；
图3是本发明实施例中阻容混联分压器结构图；
图4是本发明实施例中阻容均压组件结构图；
图5是本发明实施例中宽频电压互感器结构图；
图6是本发明实施例中信号采集模块结构图；
图中，1-金属法兰，2-空心绝缘子，3-阻容均压组件，4-固定法兰，5-阻容混联分压器，6-绝缘介质，7-底座，8-信号采集模块。
具体实施方式
下面结合附图对本发明作进一步详细说明。
本发明实施例提供了一种宽频电压互感器，其具体结构图如图5所示，其包括空心绝缘子2、金属法兰1、固定法兰4、阻容均压组件3、阻容混联分压器5、底座7和信号采集模块8；
其中，空心绝缘子2两端安装金属法兰1，空心绝缘子2顶端的金属法兰与一次系统连接，空心绝缘子2底端的金属法兰与底座7连接；金属法 兰1的内壁安装固定法兰4，阻容均压组件3两端分别与固定法兰4连接；阻容混联分压器5两端分别通过金属法兰1与一次系统和信号采集模块8连接。信号处采集模块8与底座7整体设计并安装于宽频电压互感器底部。
上述的空心绝缘子2可以设有一个，也可以设有至少两个，具体如下：
1)空心绝缘子2的数量为一个时，该空心绝缘子2两端安装金属法兰1(共2个金属法兰)，金属法兰1的内壁安装固定法兰4(即设有2个固定法兰4)，阻容均压组件3两端分别与固定法兰4连接，阻容混联分压器5两端分别通过两个金属法兰1与一次系统和信号采集模块8连接；
2)空心绝缘子2的数量为至少两个时，至少两个空心绝缘子依次串联，每个空心绝缘子两端安装金属法兰1，金属法兰1的内壁安装固定法兰4，阻容均压组件3两端分别与固定法兰4连接。
在本申请的一种可选实施例中，阻容混联分压器5一端通过第一个空心绝缘子顶端的金属法兰1与一次系统连接，另一端通过最后一个空心绝缘子底端的金属法兰1与信号采集模块8连接。
在本申请的一种可选实施例中，阻容均压组件3与阻容混联分压器5通过位于金属法兰1端面的密封圈密封于空心绝缘子2内部。
在本申请的一种可选实施例中，空心绝缘子2的具体数量由工况电压等级要求确定，阻容混联分压器5与阻容均压组件3之间以及阻容混联分压器5与固定法兰4之间均充满绝缘介质6，保持阻容混联分压器5与阻容均压组件3以及固定法兰4之间的良好绝缘；其中，作为一种示例，所述绝缘介质6可以采用绝缘油或绝缘气体。
在本申请的一种可选实施例中，空心绝缘子2内部设置的阻容均压组件3的数量具体分为以下两种情况：
1)若实际工况要求宽频电压互感器测量精度为0.2级，则每个空心绝缘子2内部设置1个阻容均压组件3；
2)若实际工况要求所述宽频电压互感器测量精度高于0.2级，则在每个空心绝缘子2内部设置2个或2个以上阻容均压组件3，阻容均压组件3并联于固定法兰4之间。
其中，宽频电压互感器测量精度为0.2级表示宽频电压互感器的电压误差为正负0.2％。
在本申请的一种可选实施例中，阻容混联分压器5结构图如图3所示，图3中，最下端的一级称之为低压臂，之上若干级构成高压臂，低压臂包括R 2、C 2和R 4，高压臂具体包括R 1、C 1和R 3，其中的R 1包括测量电阻元件R 11、R 12、…、R 1M，其中的C 1包括阻容电容元件C 11、C 12、…、C 1M，其中的R 3包括阻尼电阻元件R 31、R 32、…、R 3M。R1＝R 11+R 12+...+R 1M，C 1＝C 11∥C 12∥...∥C 1M，R3＝R 31+R 32+...+R 3M。一次电压Up作用于高压臂，低压臂输出电压Us用于连接信号采集模块8。
其中，阻容混联分压器5包括M个依次串联的阻容混联单元，阻容混联单元包括测量电容元件、阻尼电阻元件和测量电阻元件，测量电容元件与阻尼电阻元件串联后，与测量电阻元件并联。
在本申请的一种可选实施例中，阻容均压组件3结构图如图4所示，图4中，C 31、C 32、…、C 3n为均压电容元件，R 51、R 52、…、R 5n为均压电容元件，阻容均压组件3包括n个阻容均压单元，阻容均压单元包括并联的均压电阻元件和均压电容元件。
在本申请的一种可选实施例中，上述信号采集模块包括机箱以及位于机箱内部的二次分压单元、信号采集单元和电源单元，如图6所示，二次分压单元的输入端与阻容混联分压器底端连接，二次分压单元的输出端与信号采集单元的输入端连接，信号采集单元的输出端通过光纤与换流站控制室连接；
电源单元一端与信号采集单元的电源端连接，电源单元另一端与换流 站用电源连接，电源单元的数量与信号采集单元的数量相等，即每个电源单元独立为相应的信号采集单元供电。
在本申请的一种可选实施例中，上述阻容混联分压器和二次分压单元均包括多个依次串联的阻容混联单元。
在本申请的一种可选实施例中，上述阻容混联单元包括测量电容元件、阻尼电阻元件和测量电阻元件，其中测量电容元件与阻尼电阻元件串联后，与测量电阻元件并联。
在本申请的一种可选实施例中，上述二次分压单元设有一个或至少两个，每个二次分压单元独立设计，任何一个或多个二次分压单元损坏或异常，不影响其他二次分压单元正常工作。
在本申请的一种可选实施例中，上述二次分压单元为至少两个时，至少两个二次分压单元并联，每个二次分压单元的输入端与阻容混联分压器底端连接，每个二次分压单元的输出端与信号采集单元的输入端连接。
在本申请的一种可选实施例中，上述信号采集单元包括一个或至少两个信号采集器，每个信号采集器独立供电，各个信号采集器的信号输出相互没有影响。
在本申请的一种可选实施例中，所述信号采集单元包括至少两个信号采集器时，至少两个信号采集器并联，每个信号采集器的输入端与二次分压单元连接，每个信号采集器的输出端与换流站控制室连接。
在本申请的一种可选实施例中，所述电源单元包括一个或至少两个，若电源单元为至少两个时，每个电源单元为每个信号采集器供电。电源单元间相互独立工作，独立走线，各电源间互不干扰。任何电源模单元块损坏或异常，不影响其他电源单元正常工作。
在本申请的一种可选实施例中，上述信号采集单元与底座采用一体化设计，且其布置于底座7内部或紧靠底座7。
在本申请的一种可选实施例中，上述信号采集单元输入端输入的电压范围为其额定输入信号的至少3倍。
本发明实施例提供的高精度、快速响应、高可靠性、免现场效验的宽频电压互感器主要基于如下三项技术：
1)宽频电压测量技术：根据波过程理论及波阻抗匹配技术，本发明提出如图3所示的阻容混联分压器5，阻容混联分压器5包括M个依次串联的阻容混联单元，阻容混联单元包括测量电容元件、阻尼电阻元件和测量电阻元件，测量电容元件与阻尼电阻元件串联后，与测量电阻元件并联。采用阻容混联分压器5的电压互感器具有对直流电压、低频交流电压、高频电压信号的测量能力，实现了对于电压信号的宽频、快速测量，测量带宽可达2MHz以上，响应时间小于25us，拓宽了电压互感器应用领域和应用场合(可应用于传统直流输电工程、柔性直流输电工程、交流输/配电工程、高速铁路电网及任何具有宽频电压信号测量需求的领域和场合)。
2)多级阻容均压技术：
本发明实施例采用了多级级联的阻容均压组件3，阻容均压组件3包括n(n为正整数)个阻容均压单元，阻容均压单元包括并联的均压电阻元件和均压电容元件。使用多节串联空心绝缘子代替现有的单支空心绝缘子，每节空心绝缘子内部并联安装阻容均压单元，阻容均压单元两端分别与对应空心绝缘子两端的固定法兰4连接，则与各节空心绝缘子并联的阻容均压单元从上到下也是串联关系，与阻容混联分压器5共同密封于空心绝缘子内。阻容均压单元与处于同一节空心绝缘子内的阻容混联分压器5没有电气连接。由于阻容均压组件3封装于空心绝缘子内部，不受外部污秽环境影响，放置于其内部的电阻元件可将各节空心绝缘子的轴向(垂直方向)直流电位进行箝位，使空心绝缘子在轴向上具有较为均匀的电位分布。通过采用多级级联的阻容均压组件3有效减小了径向(水平方向)上空心绝 缘子与阻容混联分压器5的电位差，进而改善了空心绝缘子局部的电场分布，有效避免空心绝缘子外侧发生闪络，以及空心绝缘子与内部阻容分压器、阻容均压电容器间发生击穿故障，显著提高了宽频电压互感器产品污秽耐受等级。
本发明实施例采用了多级级联技术，用多支较短的空心绝缘子取代单支较长的空心绝缘子，则金属法兰数量较现有技术增加了2N-2个(N代表空心绝缘子数量)，即金属法兰有2N个。空心绝缘子数量越多，金属法兰的数量则越多。金属法兰材料的比热远远大于空心绝缘子材料，空心绝缘子数量的增多有利于迅速散热，降低电压互感器内部温升，减小了电阻的阻值偏移，提高了直流电压测量精度，显著拓宽电压互感器产品使用温度范围(-40℃至+70℃)，提高宽频电压互感器的运行可靠性。
3)附加误差消减技术：
直流电压互感器高压臂与周围的接地体或带电体之间存在空间杂散电容，在低频及高频交流电压作用下，杂散电容电流流出或流入高压臂，导致电压测量误差。这种误差称为附加误差，附加误差随着电压等级的增高而加大。
本发明实施例采用多级级联阻容均压组件3，在每节空心绝缘子两端并联阻容均压组件，阻容均压组件3包括n个阻容均压单元，阻容均压单元包括并联的均压电阻元件和均压电容元件。均压电阻元件的作用是使电压互感器空心绝缘子轴向电位均匀分布。均压电容元件的作用有两点：①防止均压电阻元件受各种暂态过电压(包括雷电过电压)的影响而导致均压电阻元件损坏；②利用均压电容元件可以阻断从阻容分压组件通过杂散电容流出或流入的电流。阻容混联分压器5与阻容均压组件3之间没有任何电气连接。对地的电容电流和空心绝缘子表面的泄漏电流均由阻容均压组件3提供，不经过阻容混联分压器5，使阻容混联分压器5处于完善的屏蔽 状态，最大程度减小附加误差，保证低频、高频交流电压信号测量的高精度。
本发明实施例将信号采集单元与电压互感器一体化设计，在低压侧将现有电压互感器的电信号转化成光信号，并通过光缆将光信号长距离传输至控制室。通过该技术彻底解决了电信号经电缆传输时受杂散电容干扰带来附加误差干扰的问题，进一步减小了附加误差，提高了电压信号的测量精度。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (18)

  1. 一种宽频电压互感器，包括：空心绝缘子、金属法兰、固定法兰、阻容均压组件、阻容混联分压器、底座和信号采集模块；
    所述空心绝缘子两端安装金属法兰，所述空心绝缘子顶端的金属法兰与一次系统连接，所述空心绝缘子底端的金属法兰与所述底座连接；
    所述金属法兰的内壁安装固定法兰，所述阻容均压组件两端分别与所述固定法兰连接；
    所述阻容混联分压器顶端与所述一次系统连接，所述阻容混联分压器底端与所述信号采集模块连接。
  2. 根据权利要求1所述的宽频电压互感器，其中，所述阻容均压组件包括n个阻容均压单元，所述阻容均压单元包括并联的均压电阻元件和均压电容元件；其中，n为正整数。
  3. 根据权利要求1所述的宽频电压互感器，其中，所述阻容均压组件与所述阻容混联分压器通过位于金属法兰端面的密封圈密封于空心绝缘子内部。
  4. 根据权利要求1所述的宽频电压互感器，其中，所述阻容混联分压器与阻容均压组件之间以及阻容混联分压器与固定法兰之间均充满绝缘介质，所述绝缘介质采用绝缘油或绝缘气体。
  5. 根据权利要求1所述的宽频电压互感器，其中，所述空心绝缘子的数量由工况电压等级要求确定。
  6. 根据权利要求1所述的宽频电压互感器，其中，若实际工况要求宽频电压互感器测量精度为0.2级，则每个空心绝缘子内部设置1个阻容均压组件；
    若实际工况要求所述宽频电压互感器测量精度高于0.2级，则在每个空心绝缘子内部设置2个或2个以上阻容均压组件，所述阻容均压组件并联 于固定法兰之间。
  7. 根据权利要求1-6任一所述的宽频电压互感器，其中，所述空心绝缘子设有一个或至少两个。
  8. 根据权利要求7所述的宽频电压互感器，其中，所述空心绝缘子的数量为至少两个时，至少两个空心绝缘子依次串联，每个空心绝缘子两端安装金属法兰，所述阻容均压组件两端分别与固定法兰连接；
    所述阻容混联分压器一端通过第一个空心绝缘子顶端的金属法兰与一次系统连接，所述阻容混联分压器的另一端通过最后一个空心绝缘子底端的金属法兰与所述信号采集模块连接。
  9. 根据权利要求1所述的宽频电压互感器，其中，所述信号采集模块包括机箱以及位于机箱内部的二次分压单元、信号采集单元和电源单元；
    所述二次分压单元的输入端与所述阻容混联分压器底端连接，所述二次分压单元的输出端与所述信号采集单元的输入端连接，所述信号采集单元的输出端通过光纤与换流站控制室连接；
    所述电源单元一端与所述信号采集单元的电源端连接，所述电源单元另一端与换流站用电源连接。
  10. 根据权利要求9所述的宽频电压互感器，其中，所述阻容混联分压器和二次分压单元均包括多个依次串联的阻容混联单元；
    所述阻容混联单元包括测量电容元件、阻尼电阻元件和测量电阻元件，所述测量电容元件与阻尼电阻元件串联后，与测量电阻元件并联。
  11. 根据权利要求9所述的宽频电压互感器，其中，所述二次分压单元设有一个或至少两个。
  12. 根据权利要求11所述的宽频电压互感器，其中，所述二次分压单元为至少两个时，至少两个二次分压单元并联，每个二次分压单元的输入端与阻容混联分压器底端连接，每个二次分压单元的输出端与信号采集单元 的输入端连接。
  13. 根据权利要求9所述的宽频电压互感器，其中，所述信号采集单元包括一个或至少两个信号采集器。
  14. 根据权利要求13所述的宽频电压互感器，其中，所述信号采集单元包括至少两个信号采集器时，所述至少两个信号采集器并联，每个信号采集器的输入端与二次分压单元连接，每个信号采集器的输出端与换流站控制室连接。
  15. 根据权利要求13所述的宽频电压互感器，其中，所述电源单元包括一个或至少两个。
  16. 根据权利要求15所述的宽频电压互感器，其中，所述电源单元为至少两个时，每个电源单元为每个信号采集器供电。
  17. 根据权利要求9所述的宽频电压互感器，其中，所述信号采集单元与底座采用一体化设计，且其布置于所述底座内部或紧靠所述底座。
  18. 根据权利要求9所述的宽频电压互感器，其中，所述信号采集单元输入端输入的电压范围为其额定输入信号的至少3倍。
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