Benoît Robyns

Experimental Validation of Energy Storage System Management Strategies for a Local DC Distribution System of More Electric Aircraft

The local DC power distribution system of More Electric Aircraft is one of the cores of the electric power transmission. Because the mechanical source (turbine engine) is unidirectional, the system is not totally reversible. Some storage and dissipation systems are necessary to store or/and dissipate the returned energy to maintain the dc bus voltage. Different power-management strategies are proposed and compared. The development of experimental test benches is necessary to validate these strategies. In this paper, we present a 3-kW test bench, emulating a unidirectional source that supplies a bidirectional load with the help of a hybrid system using supercapacitors and a dissipation system. The experimental validation of the power-management strategies is presented in this paper, too.

A methodology to design a fuzzy logic based supervision of Hybrid Renewable Energy Systems

Hybrid Renewable Energy Systems (HRES) are increasingly used to improve the grid integration of wind power generators. The goal of this work is to propose a methodology to design a fuzzy logic based supervision of this new kind of production unit. A graphical modeling tool is proposed to facilitate the analysis and the determination of fuzzy control algorithms adapted to complex hybrid systems. To explain this methodology, the association of wind generators, decentralized generators and storage systems are considered for the production of electrical power. The methodology is divided in six steps covering the design of a supervisor from the system work specifications to an optimized implementation of the control. The performance of this supervisor is shown with the help of simulations. Finally, the application of this methodology to the supervision of different topologies of HRES is also proposed to bring forward the systematic dimension of the approach.

Original article: Methodologies for supervision of Hybrid Energy Sources based on Storage Systems - A survey

Hybrid Energy Sources based on Storage Systems (HES) are increasingly used to improve the grid integration of renewable energy generators, or to improve the energy efficiency and the reliability of transport systems. This paper proposes a survey on the methodologies to design fuzzy logic based supervision strategies of this new kind of energy generating systems. Different ways to manage energy storage system are particularly discussed. A graphical modeling tool is used to facilitate the analysis and the determination of fuzzy control algorithms adapted to complex hybrid systems. The methodology is divided in different steps covering the design of a supervisor from the system work specifications to an optimized implementation of the control. An Experimental Design Methodology (EDM) combined with optimization algorithms is used to tune a set of parameters suitable for a fuzzy supervisor in order to optimize power, energy, efficiency, voltage quality, economic or environmental indicators. The application of this methodology to the supervision of different topologies of HES, based on renewable energy in a grid or in building applications or dedicated to transport systems, illustrates the performance and the systematic dimension of the approach.

Association of wind turbine based dispersed generators and storage systems to participate in primary frequency control

The goal of this work is to develop a supervision strategy for hybrid generation systems. This strategy must allow to improve the grid insertion of wind turbine generators (WTG) by associating them some storage systems and foreseeable decentralized generator (FDG). To maintain a reference power and to contribute to the primary frequency control with a hybrid generator based on variable speed WTG, storage systems and FDG, a fuzzy logic supervisor is proposed. A detailed method to build this supervisor is proposed. The performance of this supervisor is shown with the help of simulation.

Original Articles: Experimental design and genetic algorithm optimization of a fuzzy-logic supervisor for embedded electrical power systems

The embedded power systems are nowadays developing at high pace. Hybrid-electric vehicles, full-electric vehicles, airplanes, ships, high-speed trains, all share a common point - the embedded electrical power system. This paper aims to present an optimization methodology of a fuzzy-logic supervision strategy. The optimization objectives are to minimize the DC-link voltage variations, and to increase the system efficiency by reducing the dissipated power. For that, a methodology involving the experimental design and genetic algorithm will be presented. The simulation and experimental results are validating the proposed procedure.

Influence of wind turbines on power system reliability through probabilistic studies

With the fast pace of wind development, the reliability of the power system will be affected in the near future because wind power is a highly variable energy source. This paper uses a probabilistic method for short-term reliability evaluation of a composite generation and transmission system that include a large amount of wind power. This method allows us to consider almost all possible cases, with their probability of occurrence, in order to estimate the risk of not meeting system requirements; such as voltage constraints, line congestion, etc. A reliability assessment is implemented on a regional network medium-voltage based on day-ahead wind speed forecast. The ratio of the wind power absorbed by system to the available wind power shows the compatibility of network with wind turbines. The reliability responsibility of each element in the network can also be identified by analyzing the causes of system failure during the simulation process. Furthermore, capacity credit of wind energy is estimated thanks to a reliability aspect comparison between classical generators and wind turbines.

Supervision of renewable energy for its integration in the electrical system

As renewable electricity generation is increasing, several concerns are addressed by the Transmission System Operators (TSO) towards the management and the security of the electrical grid. This paper reviews solutions to ease the integration of renewable energy in the electrical systems through enhanced supervision of renewable generation as well as utilisation of short term or medium term storage system. Amount these solutions, supervision and storage allow to smooth output power, avoid congestion and participate in primary frequency control. Dynamic power system simulations are shown to illustrate the efficiency of the supervision methods.

Design and operation optimization of a hybrid railway power substation

Railway traffic increases and electricity market liberalization constrain the railway actors to consider new solutions to handle the energy consumption. Hence, a technology change in the railway electrical systems is considered through the integration of renewable energy sources and storage units. In this context, a relevant methodology is proposed here for optimal design and operation analysis of railway hybrid power substations. This method is useful for the analysis and improvement of future railway power network efficiency.

Integration of renewable energy in the European power grid: Market mechanism for congestion management

With the increased use of wind energy several Transmission System Operators (TSO) have increasing difficulties for congestion forecasting due to the unpredictable nature of the energy source. To maintain the state of the system within acceptable and secure operating conditions, the TSOs require the curtailment of the production of generators to avoid local congestion on the power grid. These actions reduce the revenue of renewable producers and limit the development of green energy. This is because renewable producers with support schemes bear the inherent cost of congestion when they are re-dispatched. This paper proposes two types of market mechanism that solve the above mentioned problems in case of local congestion. The first mechanism consists in a compensation between renewable producers to limit the amount of redispatched generation in situations when the local congested power grid incorporates only renewable production. If both renewable and conventional productions are connected close to each other, a second mechanism will be used to incentivize competition among power adjustment offers.

Multi-criteria fuzzy-logic optimized supervision for hybrid railway power substations

Renewable energy sources and storage units’ integration in the railway power substations is an alternative solution to handle the energy consumption, due to railway traffic increase and electricity market liberalization. To integrate this technology change in the railway network, an adapted energy management system has to be established. However, when considering only energy efficiency aspects on the energy management strategy, an economical viable solution cannot be ensured. This paper proposes a supervision strategy based on multi-criteria approach including energetic, environmental and economic constraints. The energy management objectives such as reducing the network power demand, favoring local renewable consumption and ensuring storage availability are treated in different time levels. Economic aspects are first integrated in predictive mode based on forecast data. Then a supervision strategy is developed based on fuzzy logic approach and graphical tool to build it. An optimization study of the supervision strategy is proposed in order to conclude on system performance. Simulation results are discussed for different scenarios cases and the reaction of the hybrid railway power substation is detailed. Results show that this methodology can be successfully applied for hybrid systems energy management in order to improve their energy efficiency.