Professor Emeritus at the University of Le Havre Normandy, France
By Prof. Cristianis Nichita, Professor Emeritus at the University of Le Havre Normandy, France.
Many research papers on distributed generation from different countries have been collected and categorized. The main topics discussed are DG and it impacts on mesh and radial electricity supply, flexibility in electricity demand, and integration opportunities on the utility system. Most of researches are still in tables; only a few were actual business cases or in field-test level. Although, many optimization algorithms to find the best location and size of DG have been proposed, but are not publicly available yet. According to market rules, the integration of different generation units differ between countries but we conclude three main points:
• The simplest network structures to protect are radial systems while meshed distribution networks have a higher short circuit power.
• The advantage of meshed networks is relatively balanced voltage profile and high reliability through redundancy.
• Most of distributed generators (as wind and tidal energy) feed either into mesh structure, usually used with high or medium voltage, while radial used with low-level voltage, which is mostly for PV.
The motivations adducted to increase the penetration of DG and wind energy and market development are:
• Reducing of cost of production when demand increased which make business area more interested to apply these researches and developing tools can be used for this field.
• The successful integration for DG’s inside different type of distribution system from the technical and economic views will change rules of markets.
• Select optimum location and size according to different structure of distribution system will change the cost.
The main objective of research works is to study the concept of offshore wind / tidal turbine hybridization based on the flexibility of a multi-function emulator that allows various emulation architectures: wind turbines, tidal turbines, and hybrid wind – tidal turbines systems. We analyze its impact on the output power of the system; the obtained results are correlated with wind and tidal speed profiles, in which statistical properties impacting global power chains could be complementary and in particular in a function of the given sites.
• In order to reduce real-time simulation with minimum distortion in output results, we develop a methodology called “accelerated simulation time” by simulation method followed its experimental validation on emulators systems. Finally, yet importantly, wind and tidal hardware simulators available in GREAH are presented. The modelling of both turbines is based on their functional similarities, the main difference lies in the density of resources (Air and Water).
• We introduce the concept of hybrid offshore wind /tidal turbines based on an electro-mechanical coupling and the methodology of a virtual time called “time acceleration”.
• Optimal speed control is achieved by designing two control strategies, fixed and variable speed, where a low power wind/tidal hybrid system is mechanically coupled on the DFIG shaft.
• In addition, the concept of time acceleration is described, methodology introduced for reducing simulation time with reasonable results, also this method is useful to decrease data size of wind/tidal profiles. We present HILS flexibility, through which various emulation architectures could be developed: wind turbine, tidal turbine, and wind-tidal turbines.
• An experimental simulation of a hybrid offshore wind-tidal turbine system is carried out, using a new architecture of the emulator system that we developed as part of the collaboration with a team of Korean researchers. However, the vector-controlled servomotor is used to emulate the wind turbine, while the synchronous machine is used to simulate a tidal turbine. The generator’s shaft serves as a mechanical coupling between both turbines. We have highlighted in this experiment, the hybridization of two different resources to generate electricity, and also the importance of adding a storage system to overcome the problem of voltage drop when there is not enough wind or tidal to generate sufficient electrical power.
Biography
NICHITA Cristianis is a Doctor Engineer in Control Systems from The University of Galati in Romania, he received a Doctoral degree in Electrical Engineering from The University of Le Havre in France. He is Professor Emeritus at the University of Le Havre Normandy and Professor Emeritus at University of Galati. Former GU8 (Global University 8) General Secretary, he is currently member of “European Association for the Development of Renewable Energies, Environment and Power Quality”, member of IEEE France Section, of IEEE Power & Energy Society (USA), of EEA Club (France). He has been recently appointed President of Joint Company “Normandy Interactive and Global Engineering Consulting”. He is actually Research Investigator in Renewables Energies and PhD Supervisor in GREAH Lab (Groupe de Recherche en Electrotechnique et Automatique du Havre, France).