A Single Frequency Superposition Method for Noise Test of Power Capacitor

A power capacitor, noise test technology, applied in the direction of noise figure or signal-to-noise ratio measurement, to achieve the effect of reducing the difficulty of loading

CN104375014BActive Publication Date: 2017-02-22XI AN JIAOTONG UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2017-02-22

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Abstract

The invention discloses a single-frequency overlapping method for a power capacitor noise test. The method comprises the following steps that (1) according to loaded voltage u and loaded current I of a capacitor, the frequency spectrum SU of a capacitor voltage square is computed; (2) according to the frequency spectrum SU of the capacitor voltage square, each-time single-frequency loaded voltage U(f) is computed, wherein f is the frequency of the loaded voltage; (3) the single-frequency loaded voltages U(f) with different frequencies f are loaded on the capacitor in sequence, and meanwhile the capacitor radiation sound power levels LWAf are measured in a noise elimination room; and (4) all the radiation sound power levels LWAf loaded with single frequencies are converted into sound power, then number adding is carried out, radiation power during whole loading is obtained, and then a predicated whole A weight measuring sound radiation power level LWA is obtained. According to the method, the capacitor noise test under infinite-time harmonic waves can be achieved, and a single-frequency-output frequency-variable power supply can be used for estimating the noise of the capacitor under the harmonic waves accurately.
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Description

technical field

[0001] The invention belongs to the technical field of noise testing of high-voltage power equipment, and in particular relates to a single-frequency superimposition method used for noise testing of power capacitors. Background technique

[0002] Although the power grid company has clearly stipulated the noise limit value of the AC filter capacitor device, and requires the manufacturer to provide the noise calculation report and test report in the bidding, but there is no clear requirement for the noise calculation method and test method of the capacitor device. Accurate estimation of capacitor noise level is of great significance for the selection of low-noise capacitors in engineering and the optimal design of noise reduction measures. Noise testing is the most direct way to estimate the noise level of a capacitor. The test method of loading the capacitor with the same excitation as the operating condition and then measuring its radiated noise can directly...

Examples

Embodiment

[0040] Assume that the capacitor radiation noise under the following three kinds of harmonic loading needs to be tested.

[0041] Table 1: Reference test results

[0042]

[0043] The implementation process of single frequency superposition test is as follows: figure 1 shown. During the test, first calculate the frequency spectrum of the voltage square according to the requirements of the loading voltage, then calculate the single-frequency loading voltage according to the decomposed single-frequency voltage square, apply the single-frequency voltage to the capacitor in turn, and measure the radiated sound power of the capacitor in the anechoic chamber at the same time, Finally, the radiated sound power of each single-frequency loading is superimposed according to formula (4), so as to obtain the required capacitor radiated sound power under multi-frequency loading.

[0044] Table 2: Comparison of single-frequency superposition and direct multi-frequency loading test resu...