Primal dual interior point dynamic programming for coordinated charging of electric vehicles

Coordinated charging of electric vehicles(EVs)is critical to provide safe and cost effective operation of distribution systems where household single phase charging of EV could contribute to imbalance of the distribution system.To date,reported researches on optimization methods for coordinated charging aiming at minimizing power losses have the disadvantages of low calculation efficiency when applied to large systems or have not taken the voltage constraints into account.The phase component and polar coordinates power flow equations of an unbalanced distribution system are derived.Primal dual interior point dynamic programming is introduced for coordinated charging of EVs to minimize distribution system losses where charging demand,voltage and current constraints have been taken into account.The proposed optimization is evaluated using an actual 423-bus case as the test system.Results are promisingwith the proposed method having good convergence under time-efficient calculations while providing optimization of power losses,lower load variance,and improvement of voltage profile versus uncoordinated scenarios.

Coordinating EV Charging via Blockchain

The increasing electric vehicle(EV) penetration in a distribution network triggers the need for EV charging coordination. This paper firstly proposes a hierarchical EV charging coordination model and an algorithm based on Lagrangian relaxation. A barrier to the implementation of the coordination algorithm is that there usually does not exist a reliable coordinator of charging stations. This paper shows that an unreliable coordinator may collude with some charging stations and behave dishonestly by disobeying the coordination algorithm. Thus, the collusion coalition can gain more profits while lowering the profits of others and the total social welfare. To provide reliable coordination of charging stations, a novel blockchain-based coordination platform via Ethereum is established, including a coordination structure and a smart contract. A mathematical analysis is given to show that the proposed platform can mitigate the collusion behaviors in the coordination. Simulation results show the consequence of collusion and how blockchain can prevent the collusion.

A Two-stage Autonomous EV Charging Coordination Method Enabled by Blockchain

Increasing electric vehicle(EV) penetration in distribution networks necessitate EV charging coordination. This paper proposes a two-stage EV charging coordination mechanism that frees the distribution system operator(DSO) from extra burdens of EV charging coordination. The first stage ensures that the total charging demand meets facility constraints,and the second stage ensures fair charging welfare allocation while maximizing the total charging welfare via Nash-bargaining trading. A decentralized algorithm based on the alternating direction method of multipliers(ADMM) is proposed to protect individual privacy. The proposed mechanism is implemented on the blockchain to enable trustworthy EV charging coordination in case a third-party coordinator is absent. Simulation results demonstrate the effectiveness and efficiency of the proposed approach.

Free-space optical data links based on coaxial sidelobe-modified optical vortices

We propose and demonstrate free-space optical data links based on coaxial sidelobe-modified optical vortices（CSMOVs）. In contrast to the optical communication systems based on amplitude, frequency, or phase detection, the proposed scheme uses the radii ratio between the principle ring and the first sidelobe of the CSMOV.Therefore, the demand of stringent alignment and/or accurate phase matching is released. We design and optimize a composite computer-generated hologram to generate a CSMOV with four topological charges（TCs）.Extracted from the images captured by a CCD camera, the radii ratio between the principle ring and the first sidelobe of different TCs are consistent with the theoretical values.