Abstract:
To improve the hosting capacity of distributed photovoltaic (PV) sources in rural distribution networks and prevent reverse overloading of distribution transformers and overvoltage at grid connection points caused by large-scale PV integration, this paper comprehensively considers the reverse overloading capacity of distribution transformers and the efficiency of energy storage devices. It is pointed out that when the total capacity of distributed PV sources is less than 1.5 times the rated capacity of the distribution transformer, the PV sources can be directly connected to the low-voltage distribution network. Otherwise, the transformer should be upgraded, or the PV sources should be connected at the 10 kV voltage level, or energy storage devices should be configured. The required power and energy capacities of the storage devices are also provided. A voltage regulation strategy combining on-load tap changers (OLTCs) with local control of four-quadrant operation of distributed PV sources is proposed to address the overvoltage problems on the low-voltage side of distribution transformers and at the user side. Furthermore, the efficiencies of solar water heaters and PV-based electric heating are compared, and it is shown that the combined use of solar water heaters and rooftop PV can achieve more effective utilization of solar energy.