Special transformer sharing mode: Utilizing special transformers of buildings to supply power for charging stations

Abstract

In view of the limited capacity for public transformers to accept electric vehicles (EVs) and the large cost of putting in new transformers to supply power in the parking lot of urban buildings, a special transformer sharing mode (STSM) is proposed, where charging station operators utilize the special transformers of buildings to supply power for charging stations. To enhance the applicability of STSM, single regulation and joint regulation methods for the charging price strategy of charging stations are put up, and the mathematical model of joint regulation is focused on. First of all, a joint regulation mechanism is established, in which EVs are guided to charge off-peak and off-station through the joint regulation. Secondly, integrating charging fees, queuing costs, and transfer costs, the equivalent charging prices for EV users are put forward. Based on the difference of the equivalent charging prices, transfer probability model for EVs' charging periods and charging stations is proposed. Furthermore, the overall objective of joint regulation is built based on the net income of all parties. And an optimization method for the joint regulation of charging prices is proposed. Then, regulation lifting ratio is put forward to reflect the superiority of joint regulation over single regulation. Based on this, an evaluation model for joint station diameter threshold is established. The practical result proves that through single regulation and joint regulation, approximately 200-500 additional EVs can be powered, which will result in significant savings in infrastructure construction and investment costs.

Operation optimization of battery swapping stations with photovoltaics and battery energy storage stations supplied by transformer spare capacity

“…A lot of studies on orderly charging of charging stations and BSS have been proposed [12]. In [13], the capacity and location planning of charging stations are discussed.…”

“…where P 0 is the rated charging power of EV, P PV t denotes the output power of PV at time t; ⌊⋅⌋ denotes rounding down;S r (t ) is the spare capacity of special transformers at time t. The spare capacity is defined as follows [12]:…”

“…Then we have $$$$\begin{equation}{N}_{\mathrm{r}}(t) = \left\lfloor {({S}_{\mathrm{r}}(t) - P_t^{\mathrm{B}} + P_t^{{\mathrm{PV}}})/{P}_0} \right\rfloor \end{equation}$$$$where P 0 is the rated charging power of EV, $$P_t^{{\mathrm{PV}}}$$ denotes the output power of PV at time t; $$\lfloor \cdot \rfloor $$ denotes rounding down;$${S}_{\mathrm{r}}(t)$$ is the spare capacity of special transformers at time t . The spare capacity is defined as follows [12]: $$$$\begin{equation}{S}_{\mathrm{r}}(t) = 0.8{S}_{{\mathrm{z}}0} - {P}_{\mathrm{l}}(t)\end{equation}$$$$where S z0 is the capacity of the building special transformer, and $${P}_{\mathrm{l}}(t)$$ indicates the building load in time t .…”