Traceability of Voltage Measurements for Non-Sinusoidal Waveforms

The authors have recently developed a number of instruments for measuring harmonic composition of power grid signals. These instruments have a simple, predominantly digital architecture and they are based on an assumption that the frequency of the measured signals equals its nominal value (50 Hz, 60 Hz or 400 Hz). This approach has enabled the measurement of a high number of harmonics within a single period. However, the internal oscillator in the instrument generates the nominal frequency and cannot adapt to frequency changes in the input signal. This paper presents a method for the improvement of the operation of the developed instruments in cases when the fundamental frequency drifts from its nominal value as is the case with real power grid signals. Based on this method, modified versions of the harmonic measurement instruments have been developed. A comparison of the measurement error with and without the application of the proposed method is presented in the paper.

Section: Introductionmentioning

confidence: 99%

A Method for Harmonic Measurement of Real Power Grid Signals with Frequency Drift using Instruments with Internally Generated Reference Frequency

Antić¹,

Mitrovic²,

Vujičić³

2012

“…The new proposed Averaging two subsets method can be used in applications where both high precision and speed of RMS value measurement is important [8,9]. In future work, the method will be tested for signals with higher harmonics, presence of noise, and the influence of analog to digital converters with different conversion resolution.…”

Section: Resultsmentioning

confidence: 99%

Comparison of RMS Value Measurement Algorithms of Non-coherent Sampled Signals

Hegeduš¹,

Mostarac²,

Malarić³

2011

“…High precision and speed of measurement was important [15,16]. In regard to that the Omicron testing system was used in the end-to-end testing.…”

Section: A Software and Modules For End-to-end Testingmentioning

confidence: 99%

Staged-Fault Testing of Distance Protection Relay Settings

Havelka¹,

Malarić²,

Frlan³

2012

In order to analyze the operation of the protection system during induced fault testing in the Croatian power system, a simulation using the CAPE software has been performed. The CAPE software (Computer-Aided Protection Engineering) is expert software intended primarily for relay protection engineers, which calculates current and voltage values during faults in the power system, so that relay protection devices can be properly set up. Once the accuracy of the simulation model had been confirmed, a series of simulations were performed in order to obtain the optimal fault location to test the protection system. The simulation results were used to specify the test sequence definitions for the end-to-end relay testing using advanced testing equipment with GPS synchronization for secondary injection in protection schemes based on communication. The objective of the end-to-end testing was to perform field validation of the protection settings, including verification of the circuit breaker operation, telecommunication channel time and the effectiveness of the relay algorithms. Once the end-to-end secondary injection testing had been completed, the induced fault testing was performed with three-end lines loaded and in service. This paper describes and analyses the test procedure, consisting of CAPE simulations, end-to-end test with advanced secondary equipment and staged-fault test of a three-end power line in the Croatian transmission system.