Instantaneous Flicker Control Strategy with OLTC-Fitted Distribution Transformers in LV Networks

With the increasing PV penetration in Low Voltage (LV) networks, On-Load Tap Changer (OLTC) is being considered in the voltage control strategies. However, the flicker problem induced by the step voltage changes of the OLTC operation is still to be studied and its addition to the preexistent flicker (due to cloud movement and sudden load changes), can lead to the violation of voltage flicker standard. Therefore, a study is conducted quantifying the amount of flicker induced by the OLTC operation and a novel flicker control approach is presented that will stabilize the voltage level with minimum PV curtailment and least number of tapping operations. Moreover, its comparison is made with different voltage regulation techniques. A typical Finnish rural LV network is simulated in MATLAB and the sensitivity analysis is done for the variables of power ramp rate and time delay of OLTC, to fully authenticate the proposed strategy.