Rapid increase in the number of electric vehicles will likely deteriorate voltage profiles and overload distribution networks. Controlling the charging schedule of electric vehicles in a coordinated manner provides a potential solution to mitigate the issues and could defer reinforcement of network infrastructure. This work presents a method for robust, cost-minimising, day-ahead scheduling of overnight charging of electric vehicles in low voltage networks in a stochastic environment with minimal real-time adaptation. To reduce the computational complexity, a linear power flow approximation is utilised. The stochastic environment captures multiple uncertainties arising from the mobility behaviour including stochastic daily trip distances, arrival and departure times. Knowledge about the probability distributions of these parameters is used to hedge risks regarding the cost of charging, network overloading, voltage violation and charging reliability. The results on a test network provide an insight into the impact of uncertainty and the effectiveness of addressing aspects of risk during optimisation. In particular, planning with more conservative estimates of initial battery charge levels increases the reliability and technical feasibility of optimised schedules.
The low carbon transition requires the high growth of renewable generation penetration in energy systems to ultimately achieve net-zero carbon target. To ensure the reliable operation of energy systems with high intermittent renewable output, it is critical to have sufficient flexible resources to avoid curtailment. Therefore, the integrated power-natural gas-heating energy systems with power to gas (P2G) and gas storage has attracted great research interest especially on the combined operation method to enhance the flexibility provision between each other. In this paper, taking heating demand, P2G and gas storage into consideration, a multi-objective optimal operation strategy of integrated power-natural gas-heating energy systems is presented to obtain the maximum economic and environmental benefits. Furthermore, a novel model of flexibility metric is proposed based on redundant linepack and gas storage. Case studies without P2G and with P2G are carried out on integrated IEEE 39-bus power and Belgian 20-node gas system. Simulation results demonstrate that P2G not only can be beneficial for operation of the integrated energy systems in terms of total operational cost decline from M$2.510 to M$2.503, CO2 emission reduction from 62,860 ton to 62,240 ton and wind curtailment decrease from 25.58% to 4.22% but also has significant effect on flexibility improvement of a 71.72% increase.
11 November 2021 in IEEE Transactions on Industry Applications
In recent years, the idea of green aviation and environmental protection has received increasing attention from the aviation industry. Hydrogen energy has an important role in the transition to low-carbon energy systems. To address that, this article conducts the technoeconomic analysis for the hydrogen energy system, photovoltaic energy, battery storage system, electric auxiliary power unit (APU) of aircraft, and electric vehicles (EVs) into the electrified airport energy system. Specifically, the model quantifies aircraft electrical load based on passenger’ travel behavior, establishes a corresponding APU load characteristic model, and establishes an EV charging load profile based on the flight schedule and sequencing algorithm. A mixed-integer linear programming optimization method based on life cycle theory was proposed to minimize the total costs of hydrogen-integrated energy systems for airports (HIES). However, the resilience advantages of hydrogen energy concerning power failure are little explored in existing academic research. Thus, a resilience assessment method and improvement measure were proposed for HIES. Case studies have been conducted under different optimal hydrogen energy integration configurations and disaster times with resilience assessment by considering periods when the power supply capacity of the grid is insufficient. The results show the effectiveness of the proposed method.