Metrological Characterization of Low Power Instrument Transformer Integrated in MV Recloser

Transcription

1 Metrological Characterization of Low Power Instrument Transformer Integrated in MV Recloser Nicolo Squarzoni, Prof. Lorenzo Peretto - University of Bologna Blair Kerr, Nenad Uzelac - G&W Electric Co. CIGRE 2017 Grid of the Future Symposium Cleveland, Ohio, USA October 2017

2 Key Topics Project motivation Equipment test Metrological characterization setup Test setup & results Conclusions 2

3 Project Motivation In depth testing under different operating conditions of Low Power Instrument Transformers (LPIT) integrated into MV reclosers Consideration of cabling capacitance and recloser controller affection on accuracy In accordance with JCGM 100/101 - GUM 3

4 LPIT System Tested Example of LPIT and Recloser Installation Photograph of MV recloser and recloser control 4

5 LPIT System Tested Passive Sensors Active Sensors 5 - Simple with few components - No power required - Less accurate - Requires correction factors - Impacted by cable length, temperature, etc. - More complex, but more accurate - Requires DC power supply - No correction factors - Less impacted by cable length, temperature, etc.

6 Metrological Characterization Hardware Setup High Voltage MV Recloser & LPIT Step Up Transformer 0.1 Class Reference Transformer NI DAQ USB Interface Variable AC Power Source 6

7 Voltage Error Percentage and Phase Error Computation NI LabVIEW Software FOR LOOP (n) times LPIT Analog Reference Analog NI 9233 ADC Hardware LPIT Digital Reference Digital SENSOR RATIO REFERENCE RATIO REFERENCE RATIO AND ADJUSTMENT FAST FOURIER TRANSFORM FAST FOURIER TRANSFORM ERROR ERROR 7

8 Type A Uncertainty Evaluation FOR LOOP (n) times LPIT Reference FAST FOURIER TRANSFORM FAST FOURIER TRANSFORM ERROR ERROR MEAN AND STANDARD DEVIATION µ σ sqrt(n) X 2 STANDARD UNCERTAINTY MEAN AND µ STANDARD DEVIATION σ sqrt(n) X 2 STANDARD UNCERTAINTY 95% TYPE A UNCERTAINTY 95% TYPE A UNCERTAINTY 8

9 Type B Uncertainty Evaluation LPIT FAST FOURIER TRANSFORM FOR LOOP (n) times DAQ Error Propagation ERROR ERROR FREQUENCY DISTRIBUTION 95% COVERAGE INTERVAL TYPE B UNCERTAINTY Reference DAQ Error Propagation FAST FOURIER TRANSFORM Reference Transformer Error Propagation ERROR 95% COVERAGE INTERVAL TYPE B UNCERTAINTY ERROR FREQUENCY DISTRIBUTION 9

10 Test Setup & Results Room temperature Basic Accuracy Test Results Rated frequency (60 Hz) Three different cable configurations: no cable 10 ft cable 100 ft cable 10

11 Basic Accuracy Test Results No impact of cable on magnitude or phase measurements 11

12 Accuracy vs. Temperature Test Setup Temperature -40 C to +65 C 20 C Steps Rated frequency (60 Hz) Three different cable configurations: No cable 10 ft cable 100 ft cable 60C 40C Temperature (C) 20C 0C -20C -40C 12 Time

13 Accuracy vs. Temperature Test Setup High Voltage MV Recloser & LPIT 0.1 Class Reference Transformer Step Up Transformer Recloser Control USB Interface Serial Interface Variable AC Power Source 13

14 Accuracy vs. Temperature Test Results Voltage magnitude error was impacted by temperature but not cable length Phase error not significantly impacted by both temperature and cable length 14

15 Conclusions Test setup created to allow for a complete metrological characterization in accordance with the GUM Basic accuracy and temperature accuracy tests completed in different conditions to prove compliance with 0.5 accuracy class per IEC Deep understanding of the system including the LPIT, cables, control, etc. is required to guarantee compliance with 0.5 class. Setups can be used for future work including more extensive testing Harmonics Frequency Other major sources of influence on the accuracy. 15