Optimal Superconducting Coil Integrated Into PV Generators for Smoothing Power and Regulating Voltage in Distribution System With PHEVs

Nowadays, the proliferation of photovoltaic (PV) generators and plug-in hybrid electric vehicles (PHEVs) into power distribution systems highly escalates. The variable PV power and the abrupt power charging of PHEVs result in system power and voltage fluctuations. This paper presents the new application of the superconducting coil (SC), which is connected between the dc link of PV generators to solve this problem. Using the dc-to-dc converter as an interfaced circuit, the SC can share the inverters with the PV generators. In addition, the PV generators with the common SC are able to provide the smooth power output and regulate the system voltage. The PV inverters and the dc-to-dc converter are controlled by the proportional-integral (PI) controllers. The optimization of the PI parameters and SC inductance is performed, so that the power and voltage fluctuations are minimized. Simulation results indicate that the PV generators with the common SC, which has a lower SC inductance, provide the same smoothing effect on the PV power fluctuation as the superconducting magnetic energy storage (SMES) installed at the PV terminal. In addition, they give the superior voltage regulation effect to the SMES.