Wyniki wyszukiwania - BazTech

1

System for Calibrating Analogue Merging Units in Absence of Synchronization Signals

Cheng H.-M., Huang Q.-F., Ji F., Xu Q., Liu J., Tian Z.

Metrology and Measurement Systems

|

2018

|

Vol. 25, nr 1

129--138

EN

Synchronization signals are requisite for calibrating electrical measurement devices with digital output when using conventional calibration methods. However, since the signal sampling process of the analogue merging units (MUs) operating in an intelligent substation does not rely on external synchronization signals, accuracy calibration without the use of synchronization signals is of particular importance in order to guarantee the measurement accuracy in practical situations. So far, very little research on calibration systems independent of synchronization signals has been performed. This paper presents a design of the calibration system without dependence on synchronization signals. To verify the feasibility of the proposed design, the designed system and a conventional calibration system have been employed in testing the accuracy of the same analogue MU of a 0.2 accuracy class. The comparison of the test results shows that the differences of ratio errors are below 0.02%, and the maximum difference of phase errors is about 4′. This paper also provides a new efficient and significant calibration method which does not require any external synchronization signals.

2

An on-site calibration system for electronic instrument transformers based on LabVIEW

Zhang M., Li K., Wang J., He S.

Metrology and Measurement Systems

|

2014

|

Vol. 21, nr 2

257--270

EN

Electronic voltage transformers (EVT) and electronic current transformers (ECT) are important instruments in a digital substation. For simple, rapid and convenient development, the paper proposed an on-site calibration system for electronic instrument transformers based on LabVIEW. In the system, analog signal sampling precision and dynamic range are guaranteed by the Agilent 3458A digital multimeter, and data synchronization is also achieved based on a self-developed PCI synchronization card. To improve the measurement accuracy, an error correction algorithm based on the Hanning window interpolation FFT has good suppression of frequency fluctuation and inter-harmonics interference. The human-computer interface and analysis algorithm are designed based on LabVIEW, and the adaptive communication technology is designed based on IEC61850 9-1/2. The calibration system can take into account pairs of digital output and analog output of the electronic voltage/current transformer calibration. The results of system tests show that the calibration system can meet the requirements of 0.2 class calibration accuracy, and the actual type test and on-site calibration also show that the system is easy to operate with convenience and satisfactory stability.

3

System pomiarowy do wzorcowania mierników migotania światła w akredytowanym laboratorium wzorcującym

Pniewski M.

Pomiary Automatyka Kontrola

|

2013

|

R. 59, nr 7

640--643

PL

W artykule przedstawiono problematykę wzorcowania urządzeń umożliwiających pomiar wskaźnika krótkookresowego migotania światła - Pst. W szczególności zaproponowano metodę zachowania spójności pomiarowej przy odtwarzaniu wielkości odniesienia. Przedstawiono referencyjne stanowisko do odtwarzania sygnału reprezentującego wskaźnik Pst o zadanej wartości. Uwzględniono przy tym wytyczne norm IEC 17025, PN-EN 6100-4-30 oraz PN-EN 61000-4-15.

EN

A method of flickermeter calibration is presented in the paper. Also the importance of the short-term flicker indicator is discussed. The method of traceability of the reference values is analyzed. A signal source reproducing the reference value of the Pst parameter is also discussed in the paper. The problem of construction of the flickermeter and principle of its operation is described. A method of establishing of traceability of reference values is suggested. Reference workstation to reconstruct signal with determined value of Pst is described. Standards and guidelines IEC 17025, EN 6100-4-30 and EN 61000-4-15 are regarded in the analysis. Study was carried out to determine the error and uncertainty of the reconstructed reference signal of known values of Pst. Both the error and the uncertainty of reconstructed signal with flicker voltage signal are transferred directly to the error and uncertainty of the reconstruction indicator. Basing on the conclusion, carrying out the more accurate calibration of flickermeter can take place in an accredited laboratory.

4

Highly accurate calibration system for electronic instrument transformers

Tong Y., Ye G., Guo K., Li H.

Metrology and Measurement Systems

|

2011

|

Vol. 18, nr 2

315-322

EN

A high accurate electronic instrument transformer calibration system is introduced in this paper. The system uses the fourth-order convolution window algorithm for the error calculation method. Compared with Fast Fourier Transform, which is recommended by standard IEC-60044-8 (Electronic current transformers), it has higher accuracy. The relative measuring errors caused by asynchronous sampling could be reduced effectively without any special hardware technique adopted. The results show that the ratio error caused by asynchronous sampling can be reduced to 10-4, and the phase error can be reduced to 10-3 degrees when the deviation of frequency is within š0.5 Hz. The present method of measurement processing is achieved by a high-accuracy USB multifunction data acquisition (DAQ) card and virtual measurement devices, with low cost, short exploitation period and high stability.