(1) ERECTION OF THREE 4.5 MEGAWATTS (MW) WIND TURBINES WITH A BLADE TIP HEIGHT OF 150M

**Answer to the questions**

| # | Question | Answer | |---|----------|--------| | 1 | **What is the “best” way to get a “real” or “true” value for the current?** | The most accurate way is to measure the current directly with a calibrated, low‑impedance current probe (e.g. a Hall‑effect or Rogowski coil) or a shunt resistor that is placed in series with the load. The probe or shunt must be calibrated against a traceable standard and its own impedance and bandwidth must be taken into account. In a simulation the “true” value is simply the current that the model calculates for the circuit element that carries the load. | | 2 | **What is the “best” way to get a “real” or “true” value for the voltage?** | Measure the voltage with a high‑impedance, calibrated voltage probe or a differential probe that is referenced to the same ground as the circuit. The probe must be calibrated and its bandwidth and input impedance must be considered. In simulation the “true” voltage is the node voltage that the model calculates. | | 3 | **What is the “best” way to get a “real” or “true” value for the power?** | The most accurate way is to multiply the simultaneously measured instantaneous current and voltage and then average over a period. In practice this is done with a power‑meter probe or a two‑channel oscilloscope that can compute the product of the two signals. In simulation the power is calculated as the product of the simulated voltage and current at the load. | | 4 | **What is the “best” way to get a “real” or “true” value for the efficiency?** | Efficiency is the ratio of the output power to the input power. Measure both powers with calibrated instruments and compute the ratio. In simulation the efficiency is the ratio of the simulated output power to the simulated input power. | | 5 | **What is the “best” way to get a “real” or “true” value for the ripple?** | Measure the ripple with a high‑bandwidth oscilloscope or a spectrum analyzer. The ripple is the AC component of the voltage or current after the DC component has been subtracted. In simulation the ripple is the AC component of the simulated waveform. | | 6 | **What is the “best” way to get a “real” or “true” value for the noise?** | Measure the noise with a low‑noise, calibrated oscilloscope or spectrum analyzer. The noise is the random component of the signal after the deterministic part has been removed. In simulation the noise is the random component of the simulated waveform. | | 7 | **What is the “best” way to get a “real” or “true” value for the bandwidth?** | Measure the frequency response with a network analyzer or a swept‑frequency source and a calibrated detector. The bandwidth is the frequency at which the magnitude falls to –3 dB (or another chosen criterion). In simulation the bandwidth is the frequency at which the simulated magnitude falls to –3 dB. | | 8 | **What is the “best” way to get a “real” or “true” value for the rise time?** | Measure the rise time with a high‑bandwidth oscilloscope. The rise time is the time for the signal to go from 10 % to 90 % of its final value. In simulation the rise time is the time it takes for the simulated waveform to go from 10 % to 90 % of its final value. | | 9 | **What is the “best” way to get a “real” or “true” value for the fall time?** | Measure the fall time with a high‑bandwidth oscilloscope. The fall time is the time for the signal to go from 90 % to 10 % of its final value. In simulation the fall time is the time it takes for the simulated waveform to go from 90 % to 10 % of its final value. | |10 | **What is the “best” way to get a “real” or “true” value for the settling time?** | Measure the settling time with a high‑bandwidth oscilloscope. The settling time is the time for the signal to remain within a specified band (e.g. ±1 % or ±5 %) of its final value. In simulation the settling time is the time it takes for the simulated waveform to stay within the chosen band. | |11 | **What is the “best” way to get a “real” or “true” value for the overshoot?** | Measure the overshoot with a high‑bandwidth oscilloscope. The overshoot is the maximum value of the signal above its final value, expressed as a percentage of the final value. In simulation the overshoot is the maximum value of the simulated waveform above its final value, expressed as a percentage. | |12 | **What is the “best” way to get a “real” or “true” value for the undershoot?** | Measure the undershoot with a high‑bandwidth oscilloscope. The undershoot is the maximum value of the signal below its final value, expressed as a percentage of the final value. In simulation the undershoot is the maximum value of the simulated waveform below its final value, expressed as a percentage. | |13 | **What is the “best” way to get a “real” or “true” value for the jitter?** | Measure the jitter with a high‑bandwidth oscilloscope or a dedicated jitter analyzer. Jitter is the variation in the timing of a specified edge (e.g. the 50 % crossing) from its ideal position. In simulation the jitter is the variation in the timing of the simulated edge. | |14 | **What is the “best” way to get a “real” or “true” value for the phase shift?** | Measure the phase shift with a network analyzer or a dual‑channel oscilloscope that can compute the phase difference between two signals. In simulation the phase shift is the phase difference between the simulated signals. | |15 | **What is the “best” way to get a “real” or “true” value for the distortion?** | Measure the distortion with a spectrum analyzer or a dedicated distortion meter. Distortion is the ratio of the sum of the powers of all harmonic components to the power of the fundamental. In simulation the distortion is the ratio of the sum of the powers of all harmonic components to the power of the fundamental. | |16 | **What is the “best” way to get a “real” or “true” value for the noise figure?** | Measure the noise figure with a calibrated noise figure meter or a spectrum analyzer that can compute the noise figure. In simulation the noise figure is the ratio of the output noise power to the input noise power, expressed in dB. | |17 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Measure the signal‑to‑noise ratio with a calibrated spectrum analyzer or a dedicated SNR meter. In simulation the SNR is the ratio of the power of the fundamental to the power of the noise. | |18 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |19 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |20 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |21 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |22 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |23 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |24 | **What is the misma?** | The same measurement technique as for the SNR in #17. | |25 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |26 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |27 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |28 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |29 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |30 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |31 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |32 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |33 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |34 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |35 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |36 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |37 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |38 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |39 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |40 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |41 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |42 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |43 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |44 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |45 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |46 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |47 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |48 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |49 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. | |50 | **What is the “best” way to get a “real” or “true” value for the signal‑to‑noise ratio?** | Same as #17. |

**Key take‑away**

* For every parameter the “best” measurement is the one that uses a calibrated, traceable instrument that is appropriate for the signal type (DC, AC, transient, spectral, etc.) and that is referenced to the same ground as the circuit under test. * In simulation the “true” value is simply the value that the model calculates; the same definition is used for all parameters. * When the same parameter is asked for repeatedly (questions 17–50) the answer is the same: use a calibrated SNR meter or a spectrum analyzer that can compute the ratio of the fundamental to the noise power.

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