Comparison of Measurement Methods of LV Grid Access Impedance in the Frequency Range Assigned to Nb‑Plc Technologies
Abstract
:1. Introduction
2. The Effects of the Grid Impedance on Narrow Band-Power Line Communications (NB-PLC)
3. Method I: IGOR-Meter
3.1. Measurement Setup for the IGOR-Meter
3.2. Data Processing
3.3. Advantages and Limitations
4. Method II: UPV/EHU Method
4.1. Fundamentals of the Method
4.2. Signal Processing
4.3. Advantages and Limitations
5. Method III: TUD Method
5.1. Hardware
- Linear amplifier current source for grid excitation
- Integrated voltage and current measurement
- Additional voltage input for external current probes
- Automated power supply disconnection and buffering capacitor
5.2. Measurement Algorithm
5.3. Advantages and Limitations
6. Comparison of the Measurement Methods
7. Results and Analysis
7.1. Measurement Scenario
7.2. References for the Validation of the Methods
7.3. Results of the Comparison
7.4. Use of the Measurement Methods in the Field
8. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Method I (HES-SO) | Method II (UPV/EHU) | Method III (TUD) | ||
---|---|---|---|---|
Weight | Plugged: 12 Kg Battery powered 25 Kg | 5 Kg | 20 Kg | |
Supply | Plugged. Optional: battery during measurement | Battery powered (only signal generator is currently plugged) | Plugged, but internally powered during measurement | |
Need to synchronize to mains | No need of synchronization | No need of synchronization | Synchronized to mains | |
Coupling to grid | Connection | Direct connection | Via capacitive coupler | Direct connection |
Probes | External (Optional: Internal) | External | Internal (Optional: External) | |
Connection for measurement | 4-wire (current injection and voltage measurement separately) | 4-wire (current injection and voltage measurement separately) | 4-wire (current injection and voltage measurement separately) | |
Excitation source | Type and amplitude | Current (200 mA linear) | Voltage (configurable up to 10 Vpp) | Current (3 Arms linear) |
Frequency sweep | Single frequency steps (configurable) | Single tone – continuous sweep (sweep time config., typ.: 1 sec) | Single frequency steps | |
Signal acquis, | Sampling frequency | 4 MSample/s | 3.9 MSample/s | 10 MSample/s |
Amplitude resolution | 24 bits (adjusted to mains amplitude) | 15 bits/channel (adjusted to the excitation level) | 16 bits (adjusted to mains amplitude) | |
Suppression of fundamental | None | Filtering of 50/60 Hz and low-order harmonics | None | |
Signal processing | Signal processing | Dual-Phase Demodulation (Lock-In Amplifier Detection) | Fourier analysis (FFT) | Fourier analysis (DFT) |
Time windowing | -- | Configurable: Rectangular/Gaussian (Typ.: 20 ms window, 5 ms sliding window) | Rectangular, 200 ms (10 fundamental cycles length) | |
Analysis in frequency domain | Bandwidth | 1 kHz–500 kHz | 20 kHz–500 kHz | 0 kHz–200 kHz |
Frequency resolution | Configurable, from 5 Hz to 50 Hz | Configurable. Typical: 50 Hz. Best resolution: 5 Hz | 5 Hz | |
Measurement time | From 1 to 3 min (related to resolution in frequency) | Configurable (related to sweep time). Typical: 2 s | Several minutes | |
Accuracy | Methodology | Measurement emulation (HiRADDA + acquisition interface) of 1 Ω load. Tolerance on external probes considered | Comparison to impedance precision meter in measurements of precision resistances (0.5 to 50 Ω) | Measurement of a metrological calibrated 1 Ω Shunt |
Maximum error (for the whole frequency range) | In amplitude: ±6% In phase: ±10° | In amplitude: ±3% for Z > 10 Ω, ±6% for Z < 10 Ω In phase: ±5° | In amplitude: ±10% for Z < 0.2 Ω ±5% for 0.2 Ω ≤ Z < 0.5 Ω ±3% for Z > 0.5 Ω In phase: ±10° for Z < 0.2 Ω ±5° for 0.2 Ω ≤ Z< 0.5 Ω ±8° for Z > 50 Ω |
Method I (HES-SO) | Method II (UPV/EHU) | Method III (TUD) | |
---|---|---|---|
Advantages |
|
|
|
Limitations |
|
|
|
Relative Amplitude Error | Phase Error | |||||
---|---|---|---|---|---|---|
Freq (kHz) | HES-SO | UPV/EHU | TUD | HES-SO | UPV/EHU | TUD |
10 | 0.17% | - | 0.18% | 0.44° | - | 0.00° |
40 | 2.57% | 3.19% | 2.56% | 1.13° | 5.86° | 1.53° |
80 | 2.21% | 0.12% | 0.13% | 0.52° | 0.87° | 0.41° |
120 | 4.51% | 0.35% | 2.42% | 0.57° | 0.43° | 0.47° |
160 | 0.52% | 0.93% | 2.30% | 0.56° | 0.50° | 0.28° |
200 | 0.37% | 1.00% | 2.89% | 0.66° | 0.26° | 0.50° |
240 | 0.79% | 0.97% | - | 0.75° | 0.02° | - |
280 | 1.33% | 1.80% | - | 0.83° | 0.01° | - |
320 | 1.91% | 2.16% | - | 0.94° | 0.11° | - |
360 | 2.82% | 2.59% | - | 1.05° | 0.17° | - |
400 | 3.78% | 2.88% | - | 1.32° | 0.75° | - |
440 | 4.51% | 4.07% | - | 1.50° | 0.69° | - |
480 | 5.49% | 4.47% | - | 1.65° | 0.92° | - |
Average | 2.38% | 2.04% | 1.75% | 0.92° | 0.88° | 0.53° |
Relative Amplitude Error | Phase Error | |||||
---|---|---|---|---|---|---|
Freq (kHz) | HES-SO | UPV/EHU | TUD | HES-SO | UPV/EHU | TUD |
10 | 2.53% | - | 0.47% | 0.01° | - | 0.00° |
40 | 0.99% | 0.49% | 0.39% | 0.21° | 1.07° | 0.16° |
80 | 1.43% | 1.37% | 0.10% | 0.08° | 0.91° | 0.21° |
120 | 0.98% | 1.59% | 0.29% | 1.06° | 0.46° | 0.08° |
160 | 3.13% | 2.58% | 0.62% | 1.41° | 0.19° | 0.19° |
200 | 17.24% | 2.52% | 7.82% | 6.06° | 1.87° | 5.38° |
240 | 3.68% | 0.03% | - | 1.01° | 0.34° | - |
280 | 0.68% | 1.32% | - | 1.56° | 0.19° | - |
320 | 1.21% | 1.87% | - | 1.07° | 0.16° | - |
360 | 1.04% | 2.94% | - | 1.94° | 0.07° | - |
400 | 1.55% | 3.23% | - | 2.35° | 0.27° | - |
440 | 2.37% | 3.65% | - | 2.73° | 0.31° | - |
480 | 3.23% | 4.50% | - | 3.07° | 0.58° | - |
Average | 3.08% | 2.17% | 1.62% | 1.73° | 0.54° | 1.01° |
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Share and Cite
Fernández, I.; de la Vega, D.; Roggo, D.; Stiegler, R.; Capponi, L.; Angulo, I.; Meyer, J.; Arrinda, A. Comparison of Measurement Methods of LV Grid Access Impedance in the Frequency Range Assigned to Nb‑Plc Technologies. Electronics 2019, 8, 1155. https://doi.org/10.3390/electronics8101155
Fernández I, de la Vega D, Roggo D, Stiegler R, Capponi L, Angulo I, Meyer J, Arrinda A. Comparison of Measurement Methods of LV Grid Access Impedance in the Frequency Range Assigned to Nb‑Plc Technologies. Electronics. 2019; 8(10):1155. https://doi.org/10.3390/electronics8101155
Chicago/Turabian StyleFernández, Igor, David de la Vega, Dominique Roggo, Robert Stiegler, Lino Capponi, Itziar Angulo, Jan Meyer, and Amaia Arrinda. 2019. "Comparison of Measurement Methods of LV Grid Access Impedance in the Frequency Range Assigned to Nb‑Plc Technologies" Electronics 8, no. 10: 1155. https://doi.org/10.3390/electronics8101155