An Online Coordinated Charging/Discharging Strategy of Plug-in Electric Vehicles in Unbalanced Active Distribution Networks with Ancillary Reactive Service in the Energy Market

Abstract

The global acceptance and off-grid charging of plug-in electric vehicles (PEVs) are expected to grow tremendously in the next few years. Uncoordinated PEV charging can cause serious grid issues such as overloading of transformers and unacceptable voltage drops. Single-phase residential charging can also initiate or contribute to voltage unbalance conditions in the distribution networks. A potential solution and key challenge for PEV integration is shifting of the charging activities to off-peak periods. This paper proposes a new PEV coordination approach based on genetic algorithm (GA) optimization to perform online centralized charging and discharging considering transformer loading and node voltage magnitude and unbalance profiles. It allows PEV as source of active and reactive power to participate in energy market based on different prices during a day, without any degradation. Finally, the impacts of uncoordinated and the proposed GA coordinated PEV charging/discharging strategy are simulated for a real unbalanced Western Australian distribution network in the Perth solar city over 24 h.

An Insight into Practical Solutions for Electric Vehicle Charging in Smart Grid

“…GA is also another optimization algorithm that has been widely used in many research publications and previous investigations [47][48][49][50][51][52]. This algorithm is a near optimal solution and an iterative approach.…”

“…The optimal dispatch of SSC in optimization algorithms helps to improve the harmonic distortion and power quality of the power grid considering the nonlinearities of EV battery chargers [46][47][48][49][50][51][52]. A previous study [46] demonstrates a good application of SSCs in the online EV controlled strategy with MSS optimization considering EV battery chargers.…”

Participation of an EV Aggregator in the Reserve Market through Chance-Constrained Optimization

“…Jabalameli et al also studies the possibility to control the charging/discharging process of EVs in order to mitigate the voltage magnitude. By using the EVs as an active and reactive power source, they engage in energy markets without further battery degradation [11]. In [12] is proposed an optimal charging model to participate in the reserve market as a dynamic programming problem.…”

“…Equations (11) to (15) are now linearized. The linearization of the Equation (11) takes the following form:Ỹ…”

Coordinated optimisation of PEV charging with the support of reactive discharging and phase switching in unbalanced active distribution networks

“…For challenge 1, the latent capacity of PEV inverter can be used to inject reactive power and provide ancillary reactive services at no extra investment and with a faster response rate. In [24], the authors proposed an online coordination strategy of PEVs charging with the reactive discharging applied (first, to our best knowledge) at peak hours for improved network operation. For challenge 2, network unbalance profile can be effectively managed by optimally switching loads among the three phases supported by static transfer switches (STSs) [25].…”