Jonathan Sprooten

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.

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.

Inuence of technical-economic energy context for the management of wind farms and storage systems in a constrained network

This paper presents the control of wind generators and energy storage systems in a competitive market and technically constrained electrical systems. In such situations, storage systems have two purposes; the first one is to recover renewable energy which is normally cut off when line congestions are present. The second one is to increase its profitability, buying and selling energy on the market by taking advantage of price fluctuation. The optimization of the hybrid wind-storage system is realized in this paper using Iterative Dynamic Programming and considering wind production, load and price forecast one day in advance. Then, an economic study is achieved in order to show the effect of different market scenarios for both conventional or renewable production. Simulation results first show that the correct location and sizing of the storage system can increase wind production recovery. Secondly, the impact of renewable energy pricing on the management of the hybrid wind-storage system is studied. The optimization of revenues or renewable energy production is not always compatible in presence of storage and variable energy prices.

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.

Experiment of a Wind Generator Participation to Frequency Control

Abstract This paper presents a hardware implementation of the participation of a wind turbine to network primary frequency control. The increase of renewable production of electricity requires the participation of these generators to ancillary services. The proposed method, by actions on the pitch angle and the generator torque through fuzzy logic controllers, creates a power reserve. This reserve is regular on a large range of wind speeds and is constituted without any wind speed measurement. Furthermore, the proposed strategy uses this reserve in case of frequency deviation to provide additional active power to stabilise the electrical grid. The implementation of such strategy on a 2.2 kW test bench representing a wind turbine and its generator validates the practical feasibility of the method. Finally, the regularity of the reserve is shown to be weakly dependant on the dynamics of the wind turbine controls.