CN103983859A - Transformer dielectric loss and capacitance on-line measurement device - Google Patents

Abstract

The invention discloses an on-line measuring device for dielectric loss and capacitance of a transformer. The voltage output end of the dielectric loss meter is electrically connected to the primary of a test transformer, and the secondary of the test transformer is electrically connected to a cable copper bar connected to the high voltage side of the transformer to be tested. The beneficial effect of the invention is that it can achieve the purpose of saving manpower and material resources for safe operation and normal maintenance, and can well meet the requirements of innovation and efficiency creation. Adopting this device can avoid dismantling the lead wires of the transformer incoming line during the test process, without changing the physical connection state of the equipment in the substation, and effectively avoiding the transformer bushing leakage caused by the removal of the high-voltage cable leads on the high-voltage side of the transformer and the recovery process. The problem of heating of the joints after oil and power transmission is restored, the work efficiency is improved, the risk of substation test work is reduced, the safety of operators is enhanced, the safety of test work is improved, and the safe operation of the power grid is guaranteed.

Description

On-line Measuring Device for Transformer Dielectric Loss and Capacitance

technical field

The invention relates to the technical field of substation operation; in particular, it relates to a measuring device for measuring dielectric loss and capacitance of a transformer with an incoming cable.

Background technique

At present, the number of substation equipment in the jurisdiction of each power supply unit is increasing, and the maintenance work is also increasing, which has higher requirements for the test work efficiency of the staff. There have always been certain safety hazards in the work of removing the lead wires of the transformer. For example, if the wiring work is restored slightly carelessly, it will affect the normal operation of the equipment after the test. At home and abroad, although there are a large number of documents on how to carry out various tests on transformers without removing the lead wires. However, on the high-voltage side of the transformer where the cables are connected via copper bars, when conducting dielectric loss and capacitance measurement tests, due to the large capacitance of the high-voltage cables, the high-voltage cables have a great influence on the test results without removing the leads. If you want to obtain credible measurement data, you must remove the high-voltage cable leads on the high-voltage side of the transformer, which affects work efficiency. How to solve the problem of testing and testing this type of transformer without removing the lead wires has become a research that must be carried out in real work.

Contents of the invention

The technical problem to be solved by the present invention is to provide an on-line measuring device for dielectric loss and capacitance of a transformer.

The technical solution adopted in the present invention is an on-line measuring device for transformer dielectric loss and capacitance, including a dielectric loss meter, a test transformer and a transformer to be tested, the voltage output terminal of the dielectric loss meter and the primary voltage of the test transformer connection, the secondary of the test transformer is electrically connected to the cable copper bar connected to the high-voltage side of the transformer to be tested; during the test, the cable copper bar on the high-voltage side of the transformer to be tested is connected to the secondary of the test transformer, and the low-voltage side of the transformer to be tested is short-circuited to the The self-excited test line on the dielectric loss tester is connected, and the upper port of the cable inlet switch is connected to Cx on the dielectric loss tester.

The test transformer adopts a rated transformation ratio of of voltage transformers.

The beneficial effect of the invention is that it can achieve the purpose of saving manpower and material resources for safe operation and normal maintenance, and can well meet the requirements of innovation and efficiency creation. Adopting this device can avoid dismantling the lead wires of the transformer incoming line during the test process, without changing the physical connection state of the equipment in the substation, and effectively avoiding the transformer bushing leakage caused by the removal of the high-voltage cable leads on the high-voltage side of the transformer and the restoration process. The problem of heating of the joints after resuming power transmission, improving work efficiency, reducing the risk of substation test work, enhancing the safety of operators, improving the safety of test work, and ensuring the safe operation of the power grid.

Description of drawings

Fig. 1 is a schematic diagram of an on-line measuring device for dielectric loss and capacitance of a transformer according to the present invention.

In the picture:

10. Dielectric loss tester 20. Test transformer 30. Transformer to be tested. the

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

As shown in Figure 1, the on-line measurement device of transformer dielectric loss and capacitance of the present invention comprises, dielectric loss meter 10, test transformer 20 and transformer to be tested 30, the voltage output end of described dielectric loss meter 10 and the test transformer 20 The primary electrical connection, the secondary of the test transformer 20 is electrically connected to the cable copper bar connected to the high voltage side of the transformer to be tested 30; 30 After the low-voltage side is short-circuited, it is connected to the self-excited test line on the dielectric loss tester 10 , and the upper port of the cable inlet switch is connected to Cx on the dielectric loss tester 10 . The self-excited voltage output range of the dielectric loss tester 10 is generally less than 50V, and the voltage can be raised to the voltage required by the test through the test transformer 20, which is generally 10kV. The test transformer 20 adopts a rated transformation ratio of of voltage transformers.

The measurement principle is as follows. The existing dielectric loss meter is used to cooperate with the test transformer 20 to realize the dielectric loss and capacitance of the transformer 30 and the cable to be tested after two measurements.

The dielectric loss tester 10 in the prior art includes a standard loop and a loop to be tested. The standard circuit contains highly stable standard capacitors, and the circuit to be tested is composed of the equipment to be tested. During the test, the sinusoidal signals flowing through the standard loop and the loop to be tested are respectively sampled to obtain the standard capacitance signal and the medium signal to be tested. The phase of the standard capacitor is known, while the phase of the device under test is determined by the insulation of the device under test. After the two signals are amplified and filtered, the phase relationship is compared to calculate the dielectric loss value and capacitance value of the DUT.

The capacitance and dielectric loss of the transformer 30 to be tested are obtained from the first measurement. During the test, the cable is connected in series with the standard capacitance of the dielectric loss meter 10 as the standard capacitance of the circuit to be tested, and the transformer 30 to be tested constitutes the circuit to be tested. Since the capacitance of the cable is large and its dielectric loss value is relatively small, the influence of the cable on the standard capacitance and test results can be approximately ignored during the test. By comparing the phase relationship between the signals of the standard circuit and the circuit to be tested, the dielectric loss value of the transformer 30 to be tested can be obtained, and the capacitance of the transformer 30 to be tested can be calculated.

The second measurement can get the capacitance and dielectric loss of the cable. The transformer to be tested 30 whose dielectric loss and capacitance have been determined is used as a standard capacitor to form a standard circuit, and the cable is used as a circuit to be tested. In this way, the capacity ratio and the relative dielectric loss value of the cable relative to the transformer to be tested 30 can be measured. Since the dielectric loss and the capacitance of the transformer to be tested 30 have been measured for the first time, the transformer to be tested 30 can be used to calculate the cable's dielectric loss. Capacitance and dielectric loss value.

The present invention can avoid the process of removing the leads of the incoming transformer to be tested during the test process, does not change the physical connection state of the equipment in the substation, and effectively avoids the transformer bushing that is easily caused by the removal of the high-voltage cable leads on the high-voltage side of the transformer and the restoration process. Problems of oil leakage and joint heating after resuming power transmission can improve work efficiency and reduce the risk of substation test work, which not only enhances the safety of operators, but also improves the safety of test work and ensures the safe operation of the power grid.

Claims (2)

1. An online measuring device for transformer dielectric loss and capacitance, comprising a dielectric loss meter (10), characterized in that it also includes a test transformer (20) and a transformer to be tested (30), and the dielectric loss meter (10 ) is electrically connected to the primary of the test transformer (20), and the secondary of the test transformer (20) is electrically connected to the cable copper bar connected to the high voltage side of the transformer to be tested (30); during testing, the transformer to be tested (30) The cable copper bar on the high-voltage side is connected to the secondary of the test transformer (20), and the low-voltage side of the transformer to be tested (30) is short-circuited and then connected to the self-excited test line on the dielectric loss meter (10). Cx connection on Dissimeter (10). 2. An online measuring device for transformer dielectric loss and capacitance according to claim 1, characterized in that the test transformer (20) adopts a rated transformation ratio of of voltage transformers.