CN103592518A - Capacitor Dielectric Loss and Capacitance Measurement Method of Capacitive Voltage Transformer - Google Patents

Abstract

The invention discloses a method for measuring capacitor dielectric loss and capacitance of a capacitive voltage transformer, comprising the steps of grounding a high-voltage lead wire and a ground terminal of a dielectric loss tester, and short-circuiting each secondary winding of the capacitive voltage transformer; The steps of connecting the high-voltage test line; grounding the low-voltage end of the voltage dividing capacitor C2, and measuring the dielectric loss value tanδ _and the capacitance C _total ; disconnecting the low-voltage end of the voltage dividing capacitor C2 from the ground and connecting it to the dielectric loss tester Low-voltage test line, the step of measuring the dielectric loss value tanδ ₂ and the capacitance C ₂ ; the step of calculating the dielectric loss value tanδ ₁ and the capacitance C ₁ . The invention reduces the workload caused by removing high-voltage lead wires during routine maintenance tests, improves the work efficiency of staff and reduces the safety risk of maintenance test workers on the premise of ensuring accurate and reliable test data.

Description

Capacitor Dielectric Loss and Capacitance Measurement Method of Capacitive Voltage Transformer

technical field

The invention relates to the field of power equipment maintenance tests, in particular to a capacitor dielectric loss and capacitance measurement method of a capacitive voltage transformer.

Background technique

Capacitive voltage transformers (CVT for short) are widely used in substations because of their high dielectric strength, ability to reduce the steepness of lightning shock waves, no ferromagnetic resonance with the system, and the ability to double as coupling capacitors. However, except for the busbar interval, the line CVT is usually distributed on the edge of the substation, and aerial work vehicles cannot enter; and the CVT high-voltage lead wire is high, thick, long, and heavy, and the induced voltage is very high during non-full station power outages. Therefore, when the power outage time is short and the personnel are limited, removing the high-voltage lead wires and using the positive wiring method to perform routine measurements on the capacitors of the CVT will involve a large workload and considerable safety risks. However, if the high-voltage lead wire is not removed and the traditional positive wiring method is used for measurement, the measurement result will have a large error.

Contents of the invention

The purpose of the present invention is to provide a capacitor dielectric loss and capacitance measurement method of a capacitive voltage transformer, which can be measured without removing the high-voltage lead wire.

The technical scheme of the present invention is as follows: a capacitor dielectric loss and capacitance measuring method of a capacitive voltage transformer is measured using a dielectric loss tester; the high voltage end of the main capacitor C1 of the capacitive voltage transformer is connected to the high voltage lead , the low-voltage side is connected to the high-voltage side of the voltage divider capacitor C2; including

Step 1, ground the high-voltage lead wire and the ground terminal of the dielectric loss tester, and short-circuit the secondary windings of the capacitor voltage transformer;

Step 2, the step of connecting the high-voltage test line: connect the high-voltage test line of the dielectric loss tester to the high-voltage end of the voltage dividing capacitor C2;

Step 3, ground the low-voltage end of the voltage dividing capacitor C2, and measure the dielectric loss value tanδ _{sum and} capacitance C _total ;

Step 4, connect the low-voltage test line of the dielectric loss tester to the low-voltage test line after the low-voltage end of the voltage dividing capacitor C2 is disconnected from the ground, and measure the dielectric loss value tanδ ₂ and capacitance C ₂ ;

Step 5, calculate the dielectric loss value tanδ ₁ and capacitance C ₁ , where

C ₁ =C _total -C ₂ , tan δ ₁ =(tan δ _total C _total -tan δ ₂ C ₂ )/C ₁ .

Among them, the capacitive voltage transformer is a 110KV capacitive voltage transformer.

For a 220KV capacitive voltage transformer, the main capacitor C1 is composed of the upper capacitor C11 and the lower capacitor C12 connected in series. The low voltage terminal of the section capacitor C12 is connected to the high voltage terminal of the voltage dividing capacitor C2. During the measurement, the steps to connect the high-voltage test line (HV) are: connect the high-voltage test line of the dielectric loss tester to the low-voltage end of the capacitor C11 in the previous section, and other steps are the same as the measurement steps of the 110KV capacitive voltage transformer.

In the present invention, AI-6000 series automatic dielectric loss tester is used for measurement.

Technical effect of the present invention is:

1. Reduce the workload caused by the need to remove the high-voltage lead wires during the routine maintenance and test work, and improve the work efficiency of the staff on the premise of ensuring the accuracy and reliability of the test data.

2. Greatly reduce the safety risk of maintenance test staff.

Description of drawings

Fig. 1 is a line connection diagram for measuring the dielectric loss value tanδ _{sum total} capacitance C _total of a 110KV capacitive voltage transformer according to the first embodiment.

Fig. 2 is a line connection diagram for measuring the dielectric loss value tanδ ₂ and the capacitance C ₂ of the voltage dividing capacitor C2 of the 110KV capacitive voltage transformer according to the first embodiment.

Fig. 3 is a line connection diagram for measuring the dielectric loss value tanδ _{sum total} capacitance C _total of a 220KV capacitive voltage transformer according to the second embodiment.

Fig. 4 is the circuit connection diagram of measuring the dielectric loss value tanδ ₂ and the capacitance C ₂ of the lower section capacitor C12 in series with the voltage dividing capacitor C2 of the 220KV capacitive voltage transformer in the second embodiment.

Detailed ways

Figure 1 shows the line connection diagram for measuring the dielectric loss value tanδ _{sum total} capacitance C _total of a 110KV capacitive voltage transformer. When measuring, first ground the high-voltage lead wire 1 and the ground terminal 3 of the dielectric loss tester 2, short-circuit the secondary windings of the transformer, and then connect the high-voltage test line HV of the dielectric loss tester 2 to the high-voltage end of the voltage dividing capacitor C2 g, then close the grounding switch of the voltage transformer, and ground the low-voltage terminal δ of the voltage dividing capacitor C2, and then measure to obtain the total dielectric loss value tanδ _and the capacitance _Ctotal . After the measurement is completed, open the grounding switch of the voltage transformer to disconnect the low-voltage terminal δ of the voltage dividing capacitor C2 from the ground, and then connect the low-voltage test line Cx of the dielectric loss tester 2 to the low-voltage terminal δ of the voltage dividing capacitor C2, as shown in picture 2. The dielectric loss value tanδ ₂ and the capacitance C ₂ of the voltage dividing capacitor C2 are measured again. Finally, the dielectric loss value tanδ ₁ and the capacitance C ₁ of the main capacitor C1 are calculated according to the data of the two measurements, where C ₁ = C _total - C ₂ , tan δ ₁ = (tan δ _total C _total - tanδ ₂ C ₂ )/C ₁ . Through the above method, the dielectric loss value and capacitance of the main capacitor C1 and the voltage dividing capacitor C2 of the 110KV capacitive voltage transformer can be obtained without removing the high-voltage leads connected to the voltage transformer.

Fig. 3 shows the circuit connection diagram for measuring the dielectric loss value tanδ _{sum total} capacitance C _total of a 220KV capacitive voltage transformer. When measuring, first ground the high-voltage lead wire 1 and the ground terminal 3 of the dielectric loss tester 2, short-circuit the secondary windings of the capacitor voltage transformer, and then connect the high-voltage test line HV of the dielectric loss tester 2 to the capacitor in the upper section The low-voltage end of C11, that is, the connection flange between the upper capacitor C11 and the lower capacitor C12, then close the grounding switch of the voltage transformer, and ground the low-voltage end δ of the voltage dividing capacitor C2, and then measure to get the total Dielectric loss value tanδ _total capacitance C _total . After the measurement is completed, open the grounding switch of the voltage transformer to disconnect the low-voltage terminal δ of the voltage dividing capacitor C2 from the ground, and then connect the low-voltage test line C _x of the dielectric loss tester 2 to the low-voltage terminal δ of the voltage dividing capacitor C2 ,As shown in Figure 4. Measure again to obtain the dielectric loss value tanδ 2 and capacitance C 2 of the capacitor C12 in the next section and the voltage dividing capacitor C2 in series; finally calculate the dielectric loss value tanδ ₁ and capacitance _{C 1 of the} capacitor C11 in the previous section based on the data of the two measurements , where C ₁ =C _total -C ₂ , tanδ ₁ =(tanδ _total C _total -tanδ ₂ C ₂ )/C ₁ . Through the above method, the dielectric loss and capacitance of the upper capacitor C11, the lower capacitor C12 and the voltage dividing capacitor C2 of the 220KV capacitive voltage transformer can be obtained without removing the high-voltage lead wire connected to the voltage transformer.

The table below shows the results of the on-site comparative test of a 220KV capacitive voltage transformer, which is measured by AI-6000 series automatic dielectric loss tester, and the test voltage is 10KV.

The on-site comparison test shows that the method of measuring the dielectric loss and capacitance test without removing the high-voltage lead wire is feasible, and the measurement data is accurate and credible.

Claims (5)

1. A capacitor dielectric loss and capacitance measurement method of a capacitive voltage transformer, which is measured using a dielectric loss tester (2); the high voltage end of the main capacitor C1 of the capacitive voltage transformer is connected to the high voltage lead (1), The low voltage terminal is connected to the high voltage terminal (g) of the voltage dividing capacitor C2; characterized in that, comprising Step 1, ground the high-voltage lead wire (1) and the ground terminal (3) of the dielectric loss tester (2), and short-circuit the secondary windings of the capacitor voltage transformer; Step 2, the step of connecting the high voltage test line (HV): connect the high voltage test line (HV) of the dielectric loss tester (2) to the high voltage terminal (g) of the voltage dividing capacitor C2; Step 3, ground the low-voltage end (δ) of the voltage dividing capacitor C2, and measure the dielectric loss value tanδ _and the capacitance C _total ; Step 4, disconnect the low-voltage terminal (δ) of the voltage dividing capacitor C2 from the ground and connect it to the low-voltage test line (C _X ) of the dielectric loss tester (2), and measure the dielectric loss value tanδ ₂ and capacitance C ₂ ; Step 5, calculate the dielectric loss value tanδ ₁ and the capacitance C ₁ , where C ₁ = _Ctotal -C ₂ , tan δ ₁ =(tan δ _total C _total -tan δ ₂ C ₂ )/C ₁ . 2. The capacitor dielectric loss and capacitance measuring method of capacitive voltage transformer according to claim 1, is characterized in that, described main capacitor C1 is made up of upper joint capacitor C11 and lower joint capacitor C12 in series, last joint capacitor C11 The high-voltage end of the high-voltage terminal is connected to the high-voltage lead wire (1), the low-voltage end is connected to the high-voltage end of the lower capacitor C12, and the low-voltage end of the lower capacitor C12 is connected to the high-voltage end (g) of the voltage dividing capacitor C2; the high-voltage test line connected ( HV) steps are: connect the high-voltage test line (HV) of the dielectric loss tester (2) to the low-voltage end of the capacitor C11 in the previous section. 3. The capacitor dielectric loss and capacitance measuring method of a capacitive voltage transformer according to claim 1, wherein the capacitive voltage transformer is a 110KV capacitive voltage transformer. 4. The capacitor dielectric loss and capacitance measuring method of a capacitive voltage transformer according to claim 2, wherein the capacitive voltage transformer is a 220KV capacitive voltage transformer. 5. The capacitor dielectric loss and capacitance measuring method of a capacitive voltage transformer according to claim 1, wherein the dielectric loss tester (2) is an AI-6000 series automatic dielectric loss tester.

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