A Novel Power Measurement Method Using Lock-in Amplifiers

Precision in power measurement is an important factor for the billing and management of power supply and demand. However, uncertainty in power measurement by conventional methods continues to grow due to frequency fluctuations in the system caused by the imbalance in energy supply and demand and the harmonics caused by nonlinear loads. When the reliability of the measured power is poor, building a supply plan for the power demand and managing the billing for power consumption can be difficult. This paper proposes a novel technology that can accurately measure the power under the presence of the harmonics. With the proposed method, the power can be measured precisely by extracting the frequency-specific components from the system signals using lock-in amplifiers (LIAs). The validity of the proposed method is verified by comparing the power measurement results with that of ZERA COM 3003, a commercially available power measurement reference instrument.