An on-line measuring device and method for converter transformer losses

Abstract

The present invention relates to an on-line loss measurement device and method for a converter transformer. The device includes a first current sensor, a second current sensor, a line-side signal filter, a signal acquisition and analyzer, a third current sensor, a fourth current sensor and a frequency band adjustable filter. The first current sensor and the second current sensor are respectively connected to the signal acquisition and analyzer through the line-side signal filter, and the third current sensor and the fourth current sensor are respectively connected to the signal acquisition and analyzer through the frequency band adjustable filter. Compared with the prior art, the present invention has the advantages of on-line real-time measurement and high measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the measurement technology of converter transformers, and particularly to an on-line measurement device and method for the losses of converter transformers. Background Art

[0002] With the rapid development of high-voltage DC projects in China, the usage of converter transformers is increasing. The loss condition of converter transformers is related to whether the equipment operates normally. Generally, no-load tests and load tests are carried out on converter transformers at the time of factory to obtain their no-load and load losses. However, the operating conditions of converter transformers are more special than those of conventional AC transformers, and there are a large number of harmonic components in the valve-side winding, which leads to a large number of harmonic losses in their operating losses. Conventional no-load and load tests can only obtain fundamental wave losses and cannot obtain harmonic losses, resulting in a large difference between the loss values obtained from no-load and load tests and their actual operation. Summary of the Invention

[0003] The purpose of the present invention is to provide an on-line measurement device and method for the losses of converter transformers to overcome the defects existing in the above-mentioned prior art.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] According to one aspect of the present invention, an on-line measurement device for the losses of a converter transformer is provided, including a first current sensor, a second current sensor, a line-side signal filter, a signal acquisition and analyzer, a third current sensor, a fourth current sensor, and a frequency band adjustable filter. The first current sensor and the second current sensor are respectively connected to the signal acquisition and analyzer through the line-side signal filter, and the third current sensor and the fourth current sensor are respectively connected to the signal acquisition and analyzer through the frequency band adjustable filter.

[0006] As a preferred technical solution, the first current sensor is sleeved at the flange of the line-side bushing of the converter transformer to obtain the current signal I1 flowing through the line-side winding of the converter transformer.

[0007] As a preferred technical solution, the second current sensor is sleeved at the ground wire of the end screen of the line-side bushing of the converter transformer to obtain the current signal I11 flowing through the line-side bushing. According to the capacitance C1 of the line-side bushing, its impedance Z1 is calculated, and then the line-side voltage U1 = I11 × Z1 can be obtained.

[0008] As a preferred technical solution, the capacitance C1 of the line-side bushing is a commercially available bushing capacitance C1, and its capacitance value is obtained from the bushing manufacturer.

[0009] As a preferred technical solution, the third current sensor is sleeved at the flange of the valve side bushing of the converter transformer for obtaining the current signal I2 of the valve side winding during the operation of the converter transformer.

[0010] As a preferred technical solution, the fourth current sensor is sleeved at the ground wire of the end screen of the valve side bushing of the converter transformer for obtaining the current signal I21 flowing through the valve side bushing, calculating its impedance Z2 according to the valve side bushing capacitance C2, and obtaining the valve side voltage U2 = I21 × Z2.

[0011] As a preferred technical solution, the valve side bushing capacitance C2 is a commercially available bushing capacitance C2, and its capacitance value is obtained from the bushing manufacturer.

[0012] As a preferred technical solution, the grid side signal filter is a band-pass filter of 45 - 55 Hz, and after passing through the grid side signal filter, the current signal is a 50 Hz current signal without harmonic components.

[0013] As a preferred technical solution, the frequency band adjustable filter is a band-pass filter of 45 - 55 Hz.

[0014] According to another aspect of the present invention, there is provided a method for the on-line loss measurement device of the converter transformer. This method simultaneously collects the current signals of the grid side and the valve side windings and the current signal flowing through the bushing, calculates the voltage and current signals of the grid side and the valve side, obtains signals of different frequency bands through a band-pass filter, and further calculates the fundamental wave loss and harmonic loss values.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1) High measurement accuracy. It can measure and calculate the losses of the converter transformer during operation, and distinguish its fundamental wave loss and harmonic loss, thus ensuring the measurement accuracy, improving the measurement efficiency and expanding the measurement range.

[0017] 2) On-line real-time measurement, greatly improving the convenience of measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] As shown Figure 1 in the figure, an on-line measuring device for the losses of a commutation transformer includes a first current sensor 1, a second current sensor 2, a network-side signal filter 3, a signal acquisition and analyzer 4, a third current sensor 5, a fourth current sensor 6, and a frequency-band adjustable filter 7. The first current sensor 1 and the second current sensor 2 are respectively connected to the signal acquisition and analyzer 4 through the network-side signal filter 3. The third current sensor 5 and the fourth current sensor 6 are respectively connected to the signal acquisition and analyzer 4 through the frequency-band adjustable filter 7.

[0021] The first current sensor 1 is sleeved at the flange of the network-side bushing of the commutation transformer and is used to obtain the current signal I1 flowing through the network-side winding of the commutation transformer. The second current sensor 2 is sleeved at the grounding wire of the end screen of the network-side bushing and is used to obtain the current signal I11 flowing through the network-side bushing. According to the capacitance C1 of the network-side bushing, its impedance Z1 can be calculated, and then the network-side voltage U1 = I11 × Z1 can be obtained. The capacitance C1 of the network-side bushing is a commercially available bushing capacitance C1, and its capacitance value is obtained from the bushing manufacturer.

[0022] The third current sensor 5 is sleeved at the flange of the valve-side bushing of the commutation transformer and is used to obtain the current signal I2 of the valve-side winding during the operation of the commutation transformer. The fourth current sensor 6 is sleeved at the grounding wire of the end screen of the valve-side bushing and is used to obtain the current signal I21 flowing through the valve-side bushing. According to the capacitance C2 of the valve-side bushing, its impedance Z2 is calculated, and the valve-side voltage U2 = I21 × Z2 is obtained. The capacitance C2 of the valve-side bushing is a commercially available bushing capacitance C2, and its capacitance value is obtained from the bushing manufacturer.

[0023] The network-side signal filter 3 is a band-pass filter with a frequency range of 45 - 55 Hz. After passing through the network-side signal filter 3, the current signal is a 50 Hz current signal without harmonic components. The frequency-band adjustable filter 7 is a band-pass filter with a frequency range of 45 - 55 Hz.

[0024] During the operation of the commutation transformer, the first current sensor 1 obtains the current signal I1 flowing through the network-side winding of the commutation transformer, and the second current sensor 2 obtains the current signal I11 flowing through the network-side bushing. Then, according to the capacitance C1 of the network-side bushing, its impedance Z1 can be calculated, and the network-side voltage U1 = I11 * Z1 can be obtained. The capacitance value of the network-side bushing can be obtained from the bushing manufacturer. The two current signals pass through the network-side signal filter 3. After passing through the network-side signal filter 3, the current signal is a 50 Hz current signal without harmonic components. Then, it is collected by the signal acquisition and analyzer 4, and the network-side power P1 = I1 * U1 during the operation of the commutation transformer can be calculated.

[0025] Similarly, the current signal I2 of the valve-side winding during the operation of the converter transformer can be obtained through the third current sensor 5, and the current signal I21 flowing through the valve-side bushing can be obtained through the fourth current sensor 6. Then, according to the capacitance C2 of the valve-side bushing, its impedance Z2 can be calculated, and the valve-side voltage U2 = I21 * Z2 can be obtained. The capacitance value of the valve-side bushing can be obtained from the bushing manufacturer. The two signals are sent to the signal collector 4 through the frequency-band adjustable filter 7 for acquisition. Then, the fundamental wave or full-bandwidth signal can be obtained by adjusting the frequency-band range of the frequency-band adjustable filter 7. When the frequency-band adjustable filter 7 is adjusted to a band-pass filter of 45 - 55 Hz, the fundamental wave voltage and current signals of the valve side are obtained. At this time, the fundamental wave power of the valve side is calculated as P2 = I2 * U2, and the fundamental wave power loss is PJ = P2 - P1. When the frequency-band adjustable filter 7 is adjusted to the full bandwidth, that is, the filter does not work, the full-bandwidth valve-side voltage and current signals are obtained at this time. The calculated valve-side power is P21 = I2 * U2, and the full-bandwidth power loss is PQ = P21 - P1. Then, the loss caused by harmonics is PX = PQ - PJ.

[0026] The present invention simultaneously collects the current signals of the grid side and the valve-side winding and the current signals flowing through the bushings, calculates the voltage and current signals of the grid side and the valve side, obtains signals of different frequency bands through the adjustable filter, and further calculates the fundamental wave loss and harmonic loss values, so as to realize the on-line measurement of the losses of the converter transformer.

[0027] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for an on-line loss measurement device of a converter transformer, characterized in that, The device includes a first current sensor (1), a second current sensor (2), a grid-side signal filter (3), a signal acquisition and analyzer (4), a third current sensor (5), a fourth current sensor (6), and a frequency-band adjustable filter (7). The first current sensor (1) and the second current sensor (2) are respectively connected to the signal acquisition and analyzer (4) through the grid-side signal filter (3). The third current sensor (5) and the fourth current sensor (6) are respectively connected to the signal acquisition and analyzer (4) through the frequency-band adjustable filter (7). The first current sensor (1) is sleeved at the flange of the grid-side bushing of the converter transformer and is used to obtain the current signal I1 flowing through the grid-side winding of the converter transformer. The second current sensor (2) is sleeved at the ground wire of the end screen of the grid-side bushing of the converter transformer and is used to obtain the current signal I11 flowing through the grid-side bushing. According to the grid-side bushing capacitance C1, its impedance Z1 is calculated, and then the grid-side voltage U1 = I11×Z1 can be obtained. The current signal I1 and the current signal I11 pass through the grid-side signal filter (3). After passing through the grid-side signal filter (3), the current signal is a 50Hz current signal without harmonic components, which is then collected by the signal acquisition and analyzer (4), and the grid-side power P1 = I1*U1 during the operation of the converter transformer is calculated. The third current sensor (5) is sleeved at the flange of the valve-side bushing of the converter transformer and is used to obtain the current signal I2 during the operation of the converter transformer. The fourth current sensor (6) is sleeved at the ground wire of the end screen of the valve-side bushing of the converter transformer and is used to obtain the current signal I21 flowing through the valve-side bushing. According to the valve-side bushing capacitance C2, its impedance Z2 is calculated, and the valve-side voltage U2 = I21×Z2 is obtained. The current signal I2 and the current signal I21 pass through the frequency-band adjustable filter (7) and are sent to the signal acquisition and analyzer (4) for acquisition. Then, by adjusting the frequency-band range of the frequency-band adjustable filter (7), a fundamental wave or full-bandwidth signal is obtained. When the frequency-band adjustable filter (7) is adjusted to a band-pass filter of 45~55Hz, the fundamental wave voltage and current signals on the valve side are obtained. At this time, the fundamental wave power on the valve side is calculated as P2 = I2*U2, and the fundamental wave power loss is PJ = P2 - P1. When the frequency-band adjustable filter (7) is adjusted to the full bandwidth, the full-bandwidth valve-side voltage and current signals are obtained, and the valve-side power calculated is P21 = I2*U2, and the full-bandwidth power loss is PQ = P21 - P1. Then, the loss caused by harmonics is PX = PQ - PJ. The method simultaneously collects the current signals of the grid-side and valve-side windings and the current signals flowing through the bushings, calculates the voltage and current signals of the grid-side and valve-side, obtains signals of different frequency bands through a band-pass filter, and further calculates the fundamental wave loss and harmonic loss values.

2. The method according to claim 1, characterized in that, The grid-side bushing capacitance C1 is a commercially available bushing capacitance C1, and its capacitance value is obtained from the bushing manufacturer.

3. The method according to claim 1, characterized in that, The valve-side bushing capacitance C2 is a commercially available bushing capacitance C2, and its capacitance value is obtained from the bushing manufacturer.

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