Load shifting in the existing distribution network and perspectives for EV charging-case study

One of the traditional load shifting motivations in use for long time already is the two-level time-of-use tariff scheme. The nighttime lower energy has been known to provide lower cost for the homeowners who are using electric energy for space heating. The measurements of residential areas, presented in this paper, confirm that the load shift towards the times of lower pricing is used by many homeowners to benefit from this. This brings high load power peaks for the distribution network for some shorter periods after the pricing is changed. When introducing EV charging to the household loads, homeowners are likely to shift the start of EV charging time also for providing the lowest-price charging, as the cost if energy used for the EV can also be remarkable. The additional EV charging peak will be investigated in this paper and its effect to the existing network load power peak observed. Load data from existing residential network monitoring will be used as a basis for the comparison, where the time-of-use tariffs already have great impact. It will be shown that if the fixed-time tariff change is applied to domestic EV charging, this will result in rise of the short-time peak power demand peak in the network. For the distribution network operation, the uncontrolled EV charging could provide more relief than the simple two-tariff pricing case.