CN101738591B - On-site CVT integrated verification system - Google Patents

Abstract

The invention provides an on-site CVT integrated calibration system, which includes a test power supply, standard appliances, measuring instruments and a vehicle-mounted test platform. The test power supply is composed of a series reactor, an excitation transformer and a voltage regulator, and the standard appliances include high-voltage bushings. , standard voltage transformer and standard capacitor; among them, the high-voltage bushing, standard voltage transformer, standard capacitor and series reactor are designed as an integrated sulfur hexafluoride SF ₆ closed combined electrical appliance GIS, and the standard voltage transformer is designed as SF _6. Gas-insulated semi-horizontal structure; the present invention can conveniently and accurately analyze the ratio error of the on-site 220kV～500kV CVT (capacitive voltage transformer), the capacitance and dielectric loss of the capacitor voltage divider without unloading the truck. Reliable calibration, the additional error introduced by the measurement system is relatively fixed and easy to measure, and its variation is ≤0.02%.

Description

On-site CVT integrated calibration system

technical field

The invention relates to an on-site CVT integrated verification system, which belongs to the field of calibration, verification and detection of electric equipment.

Background technique

CVT (capacitive voltage transformer) is an important electrical equipment in the power grid. It is mainly composed of a capacitor voltage divider and a medium-voltage transformer. The capacitor voltage divider is composed of a porcelain sleeve and a number of series capacitors installed in it. The transformer in the sealed oil tank is composed of a compensation reactor and a damping device, and the resonance is suppressed by the damping device, and the damping device is composed of a resistor and a reactor. In power plants and substations, it is very necessary to conduct reliability and safety tests on CVTs in operation to reduce the probability of accidents. In recent years, with the continuous reform of the power industry, power generation and transmission and distribution companies operate separately, and the role of CVT in gateway measurement has become prominent. Its accuracy directly affects the trade settlement of electric energy. Therefore, the accuracy of CVT, especially CVT for gateway measurement Degree testing is gaining more and more attention. In "GB1207-1997 Voltage Transformer" and "GB/T4703-2001 Capacitive Voltage Transformer", it is required to check the capacitance, dielectric loss and proportional error of CVT of the capacitor voltage divider. At present, the 220kV ~ 500kV CVTs that have been installed or put into operation basically adopt the unloading on-site calibration method, that is, the test power supply, standard appliances and measuring instruments are transported to the site, and then re-unloaded and assembled to carry out calibration . However, because this method has to go through a series of cumbersome steps of unloading-assembly-checking-loading, it is easy to cause damage to the test equipment, and it also wastes huge manpower and material resources. The relative positions of the power supply, standard instruments and measuring instruments are not the same, which increases the uncertainty of the distribution parameters, thus causing the additional error introduced by the measurement system to be very unstable, sometimes seriously affecting the measurement results and even affecting the test results. Judgment of product performance. Moreover, with the higher CVT voltage level, the larger the size of the test equipment, this method has become more and more restrictive to the on-site verification work.

Contents of the invention

The purpose of the present invention is to improve the existing verification methods and verification systems for on-site CVT verification in terms of transportation and measurement, and to provide an on-site CVT integrated verification system that can It is convenient, accurate and reliable to check the proportional error of the 220kV～500kV CVT on site, the capacitance of the capacitor voltage divider and the dielectric loss without unloading the truck. The additional error introduced by the measurement system is relatively fixed and easy to measure. Its variation is ≤0.02%.

The technical solution of the present invention is: an on-site CVT integrated calibration system, characterized in that it includes a test power supply, a standard appliance, a measuring instrument and a vehicle-mounted test platform, and the test power supply is composed of a series reactor, an excitation transformer and a voltage regulator. Appliances include high-voltage bushings, standard voltage transformers and standard capacitors. Measuring instruments include high-voltage capacitor bridges, transformer calibrators and two load boxes. All equipment except measuring instruments are fixed on the vehicle-mounted test platform. And the high-voltage bushing, standard voltage transformer, standard capacitor, series reactor, excitation transformer and voltage regulator are connected in sequence, followed by the measurement area, and the measuring instruments are placed in the measurement area;

The high-voltage bushing, standard voltage transformer, standard capacitor and series reactor are designed as an integrated sulfur hexafluoride SF ₆ closed combination appliance GIS, in which the standard voltage transformer is designed as a SF ₆ gas-insulated semi-horizontal structure, and the series reactor The device is designed as an SF ₆ gas insulated, inverted series structure, with a tap for adjusting the sense, which is switched by a switch.

The above-mentioned on-site CVT integrated calibration system is characterized in that: the high-voltage conductor passes through the middle of the high-voltage bushing, the standard voltage transformer and the standard capacitor in sequence, the upper and lower sides of the standard capacitor include standard capacitor low-voltage electrodes, the standard voltage transformer and the standard capacitor The high-voltage conductor at the connection point of the series reactor and the low-voltage electrode of the standard capacitor form a capacitor, which is used as a standard capacitor.

The above-mentioned on-site CVT integrated calibration system is characterized in that: the standard voltage transformer includes all rated transformation ratios of 220kV-500kV CVT.

The above-mentioned on-site CVT integrated verification system is characterized in that: the vehicle-mounted test platform is a car box body.

The beneficial effects of the present invention are: 1. The standard voltage transformer is designed as an SF ₆ gas-insulated semi-horizontal structure, which provides convenience for vehicle transportation while reducing the vertical height; 2. The high-voltage bushing, standard voltage transformer, and standard capacitor And the series reactor is designed into an integrated GIS structure, which greatly reduces the manufacturing cost; 3. After adopting the integrated design, the calibration work can be carried out without unloading the truck, which improves the work rate; 4. During the measurement, the test power supply, standard equipment and measurement The position of the instrument on the test platform is relatively fixed, which reduces the uncertainty of the additional error introduced by the calibration system itself in the measurement.

Description of drawings

Fig. 1 is a schematic diagram of equipment layout of an on-site CVT integrated calibration system according to an embodiment of the present invention.

Figure 2, a schematic diagram of the equipment layout in the measurement area in Figure 1.

Figure 3, a schematic diagram of the internal structure of the integrated GIS composed of high-voltage bushings, standard voltage transformers, standard capacitors and series reactors in Figure 1.

Fig. 4(a) is a circuit diagram of CVT proportional error measurement according to the embodiment of the present invention.

Fig. 4(b) is a circuit diagram for measuring the capacitance and dielectric loss of the capacitive voltage divider in the CVT of the embodiment of the present invention.

Detailed ways

The on-site CVT integrated verification system of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Marks in Figure 1: 1-high voltage bushing, 2-standard voltage transformer, 3-standard capacitor, 4-series reactor, 5-excitation transformer, 6-voltage regulator, 7-vehicle-mounted test platform.

Marks in Figure 3: 8-high-voltage conductor, 9-ground potential shielding electrode, 10-transformer primary winding, 11-transformer secondary winding, 12-transformer core, 13-standard capacitor low-voltage electrode, 14-adjustment Inductive switch, 15-reactor core, 16-reactor inductance coil, 17-box, 18-positioning connection hole, r1-radius of high voltage conductor, r2-inner radius.

Marks in Figure 4: C1, C2—divider capacitance of the tested CVT, Lk—compensation reactor in the CVT, Y1, Y2—load box, QS—high voltage capacitor bridge, HE—transformer calibrator.

The schematic diagram of the equipment layout of the on-site CVT integrated calibration system of the embodiment of the present invention is shown in Figure 1. The on-site CVT integrated calibration system includes a test power supply, a standard appliance, a measuring instrument and a vehicle-mounted test platform 7, and the test power supply is connected in series. Reactor 4, excitation transformer 5 and voltage regulator 6. Standard appliances include high-voltage bushing 1, semi-horizontal multi-ratio standard voltage transformer 2 and high-voltage standard capacitor 3. All equipment except measuring instruments are fixed on the On the vehicle-mounted test platform 7, the high-voltage bushing 1, the semi-horizontal multi-ratio standard voltage transformer 2, the high-voltage standard capacitor 3, the series reactor 4, the excitation transformer 5 and the voltage regulator 6 are connected in sequence, and then the measurement area, the measuring instruments are placed in the measuring area, and the vehicle-mounted test platform 7 is the box body of the carriage.

It can be seen in Figure 2 that the high-voltage capacitor bridge, transformer calibrator and two load boxes in the measuring instrument are placed in the measurement area in sequence.

As shown in Figure 3, there are ground potential shielding electrodes 9 on both sides of the inner wall of the high-voltage bushing 1, and the primary winding 10 of the transformer in the standard voltage transformer 2 is wound outside the secondary winding 11 of the transformer and co-wound on the core 12 of the transformer , they are in the middle of the standard voltage transformer 2, and can be placed horizontally as a semi-horizontal type; the upper and lower sides of the standard capacitor 3 include standard capacitor low-voltage electrodes 13, and the inductance switching switch 14 and reactor in the box 17 of the series reactor 4 The inductance coil 16, the reactor core 15 and the reactor inductance coil 16 are arranged in order, and the high-voltage conductor 8 passes through the middle of the high-voltage bushing 1, the standard voltage transformer 2 and the standard capacitor 3 in turn, and is connected with the induction switching switch 14, the standard The high-voltage conductor 8 at the connection between the voltage transformer 2 and the series reactor 4 forms a capacitor with the standard capacitor low-voltage electrode 13, which is used as the standard capacitor 3 for system verification.

In the embodiment of the capacitance and dielectric loss measurement test circuit of the capacitor voltage divider as shown in Figure 4 (b), the rated voltage of the CVT $u_N=500/\sqrt{3}\mathrm{kV},$ The sum of high voltage ground capacitance and loop capacitance is about 5000pF. Voltage regulator 6 is 380V/420V, 30kVA. The excitation transformer 5 has a capacity of 25kVA, an output voltage of 0-20kV, and an output rated current of 1.25A. The series reactor 4 is designed to be four connected in series, with a capacity of 100kV/1A in a single section, one of which has 4 equalizing taps a, b, c, d, which are switched by the induction switch 14 . When designing the standard capacitor 3, record the length L of the low-voltage electrode of the standard capacitor, the inner radius r2, and the radius r1 of the high-voltage conductor, and take L=0.327m, r1=0.03m, r2=0.09m, then $\mathrm{Cs}=2\mathrm{\π}{\mathrm{\ϵ}}_{0}L/\ln \left(\frac{r2}{r1}\right)=20\mathrm{pF},$ Among them, ε ₀ =8.854×10 ^-12 F/m. Adjust the voltage of the voltage regulator 6, and increase the output voltage of the series resonance device (inductance adjustment switch 14, reactor iron core 15, reactor inductance coil 16) to 0.9~1.1U _N , then the CVT can be measured by the high voltage capacitor bridge QS Capacitance C1, C2 and dielectric loss tgδ of the medium capacitance voltage divider.

As shown in Figure 4(a), ground the low-voltage end of the standard capacitor 3, and use the "comparison circuit using standard voltage transformer 2" in the "Power Transformer Regulations" to measure the CVT through the transformer calibrator HE scale error.

Claims (4)

1. On-site CVT integrated calibration system, which is characterized in that it includes test power supply, standard appliances, measuring instruments and vehicle-mounted test platform. The test power supply is composed of series reactors, excitation transformers and voltage regulators. The standard appliances include high-voltage bushings , standard voltage transformer and standard capacitor, measuring instruments include high-voltage capacitor bridge, transformer calibrator and two load boxes, all equipment except measuring instruments are fixedly installed on the vehicle-mounted test platform, and high-voltage bushing, Standard voltage transformers, standard capacitors, series reactors, excitation transformers and voltage regulators are connected in sequence, followed by the measurement area, where the measuring instruments are placed; The high-voltage bushing, standard voltage transformer, standard capacitor and series reactor are designed as an integrated sulfur hexafluoride SF ₆ closed combination appliance GIS, in which the standard voltage transformer is designed as a SF ₆ gas-insulated semi-horizontal structure, and the series reactor The device is designed as an SF ₆ gas insulated, inverted series structure, with a tap for adjusting the sense, which is switched by a switch. 2. The on-site CVT integrated calibration system according to claim 1, characterized in that: the high-voltage conductor passes through the middle of the high-voltage bushing, the standard voltage transformer and the standard capacitor in sequence, and the upper and lower sides of the standard capacitor include standard capacitor low-voltage electrodes, The high-voltage conductor at the connection between the standard voltage transformer and the series reactor forms a capacitor with the low-voltage electrode of the standard capacitor, which is used as a standard capacitor. 3. The on-site CVT integrated calibration system according to claim 1, characterized in that: the standard voltage transformer includes all rated transformation ratios of 220kV-500kV CVT. 4. The on-site CVT integrated verification system according to claim 1, characterized in that: the vehicle-mounted test platform is a car box body.

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