A General Model for Residential Non-linear Loads Based on Dynamic Equivalent Admittance

To effectively assess the impact of harmonics generated by a large number of nonlinear loads connected on low-voltage residential distribution networks, this paper proposes a general time-domain model of residential nonlinear loads based on dynamic equivalent admittance parameters. To address the issue of abnormal spikes, namely outliers, that often appear on the waveforms of the time-domain equivalent parameters, a delayed method is adopted to establish a virtual three-phase symmetrical system. On this basis, a dynamic equivalent admittance parameter calculation method based on αβ transformation is proposed, with virtual zero-sequence current parameters being introduced to enhance the accuracy. At last, a general time-domain model of nonlinear loads is constructed to calculate the nonlinear load currents, while considering the dynamic harmonic characteristics of nonlinear load under varying states, a load model parameter updating strategy is proposed concomitantly. Validated with measured data of residential loads and simulations, the proposed model shows strong generality, dynamics and high accuracy.