Static load modeling during large frequency fluctuations: an experimental investigation with individual devices

In the past, frequency dependency has often been neglected in load modeling. However, the volatility of frequency is likely to increase in future grid scenarios. To assess novel strategies to increase flexibility in distribution grids, it becomes crucial to accurately model the power response of connected loads to larger frequency fluctuations. The experimental study presented in this paper aims to provide insights into the load behavior of modern load devices in the range 50±6 Hz. The three devices under test represent commonly used load technologies in low-voltage grids. For active and reactive power of each device, we identify three static load models based on steady-state measurements; a lookup table model as a result of interpolation, as well as an exponential model and a linear model based on curve fitting. Then, we assess whether these models can reconstruct the behavior of the devices during dynamic frequency variations. When comparing the measured and reconstructed power, we find the largest deviations for the motor-based load under test. For the power electronic-interfaced load under test, we observe that reactive power is significantly more frequency-dependent than active power. The outcomes of our study can be helpful for novel demand-side management strategies such as frequency-based power control.