Multiple energy carrier optimisation with intelligent agents

Multiple energy carrier systems stem from the need to evolve traditional electricity, gas and other energy systems to more efficient, integrated energy systems. An approach is presented, for controlling multiple energy carriers, including electricity (AC or DC), heat, natural gas and hydrogen, with the objective to minimise the overall cost and/or emissions, while adhering to technical and commercial constraints, such as network limits and market contracts. The technique of multi-agent systems (MAS) was used. The benefits of this approach are discussed and include a reduction of more than 50% in the balancing costs of a potential deviation. An implementation of this methodology is also presented. In order to validate the operation of the developed system, a number of experiments were performed using both software and hardware. The results validated the efficient operation of the developed system, proving its ability to optimise the operation of multiple energy carrier inputs within the context of an energy hub, using a hierarchical multi-agent system control structure

Microgrid architectures for low voltage distributed generation

[EN] The high penetration of distributed generators, most of them based on renewable energy sources, is modifying the traditional structure of the electric distribution grid. If the power of distributed generators is high enough to feed the loads of a certain area, this area could be disconnected from the main grid and operate in islanded mode. Microgrids are composed by distributed generators, energy storage devices, intelligent circuit breakers and local loads. In this paper, a review of the main microgrid architectures proposed in the literature has been carried out. The microgrid architectures are first classified regarding their AC or DC distribution buses. Besides, more complex microgrid architectures are shown. Both advantages and disadvantages of each one of the microgrid families are discussed.This work is supported by the Spanish Ministry of Science and Innovation under Grant ENE2012-37667-C02-01.Patrao Herrero, I.; Figueres Amorós, E.; Garcerá Sanfeliú, G.; González Medina, R. (2015). Microgrid architectures for low voltage distributed generation. Renewable and Sustainable Energy Reviews. 43:415-424. https://doi.org/10.1016/j.rser.2014.11.054S4154244

Behavior of a microgrid during the transition from grid connected to Islanded mode

Behavior of a microgrid during the control mode transition from grid connected to islanded operation «as studied. A detailed microgrid simulation model was developed. Microgrid frequency and voltage control was designed based on the most generic schemes identified after a thorough literature survey on practical microgrids. The simulation study results reveal the impact of generator inertia and the control mode transition delay on the frequency and voltage deviations and load shedding

Evaluation of protection coordination violations with the integration of distributed generators

Conventional distribution system is generally passive having a unidirectional power flow from its grid substation to the loads. With the addition of Distributed Generation (DG) in to the system, power flow becomes bidirectional and fault current increases. These can influence the existing protection schemes, which are originally designed for passive networks. This paper proposes a technique, which can be used to assess the protection coordination loss quantitatively, for a DG integrated network allowing the utility to take corrective measures

Voltage balancing and synchronization of microgrids with highly unbalanced loads

Microgrids can operate in parallel with the grid or as a power-island. They are thus, expected to perform seamless transition from islanded to parallel operation and vice versa. This paper reviews the existing DG interconnection standards for microgrid resynchronization, investigates possible simple solutions for voltage balancing, and shows that the existing synchrocheck relay with a circuit breaker is sufficient to reconnect an islanded, highly unbalanced microgrid back to the utility grid

Grid integration of large scale fixed speed wind farm considering static voltage stability

This paper addresses the influence of integrating a large-scale wind farm on static voltage stability of a power system based on the factors such as, wind speed, wind farm interconnection bus, interconnection cable length and wind farm size. Using the continuation power flow method effects of each factor were analysed and an index is proposed to locate a large scale fixed speed wind farm in a power system