Rezachek & Associates'
Energy & Environmental Resources

Utility Integration of Renewables

Control System Architectures/Strategies

Advanced Control of Energy and Power Systems Center (ACEPS) The mission of ACEPS is to conduct fundamental research and applied research supporting the technical advancement of the electric utility industry, their customers, and component suppliers in the field of electric power systems with special emphasis on the advanced/intelligent control and power quality in the generation, transmission, distribution, and utilization stages; using such research as a means of advancing graduate education. Center research projects focus on the development of an intelligent energy system that will employ advanced power electronics, enhanced computer and communications systems, new smart sensor and actuators, and smart interactive utility/customer interface systems. Examples include: electric vehicles and their impact on power quality, localized and adaptive monitoring systems for transmission and distribution networks, and intelligent automatic generation control for transient loads.

Hydrogen Generation from Stand-Alone Wind-Powered Electrolysis Systems Hydrogen, produced by the electrolysis of water, can be used either as an energy carrier (as a fuel or transmission vector) or as a storage medium. As such, it possesses a considerable potential to overcome the limitations of intermittent renewable energy sources such as solar photovoltaics and wind power. This potential is most likely to be first realized in remote, stand-alone systems where the produced hydrogen can be most economically utilised. At present, the use of hydrogen as a storage medium for solar power utilization is at the research and development stage. By contrast, in spite of the large European wind resource, wind-hydrogen systems have largely been considered in only theoretical terms. A particular problem is that of matching the irregular power output from a wind turbine to the smoother input requirements of an electrolyser and hydrogen storage plant. The main objectives of this project are to design and build a small scale (<10kW), standalone, wind hydrogen production system and to assess the best control strategy to adopt for the wind turbine.

Optimization of a Photovoltaic/Battery System with a Back-Up Generator Energy systems that combine solar cells with battery storage and a motor generator form an important potential market for the use of solar cells in Europe and the developing countries. The prospects for such hybrid systems are particularly good for applications in which the energy supply has to be very reliable, such as telecommunications, and in places with high levels of irradiation where a motor generator is already in use. The market for these PV/motor hybrid systems is expected to amount to 30-100 MWp by the year 2000. There is as yet little experience with these types of systems. In order to ensure that they operate effectively, it is important that the components have the correct dimensions and that the system is operated using a suitable control strategy.

Power and Power Electronics The research program in the power and power electronics area makes use of new developments in power systems, machine and converter analysis, new power semiconductor devices, and alternative energy sources to study power system harmonics and low harmonic rectifiers, to optimize induction motors, and to design high density switching power supplies.

Variable Speed Operation of Generators With Rotor-Speed Feedback in Wind Power Applications The use of induction generators in wind power applications has been common since the early development of the wind industry. Most of these generators operate at fixed frequency and are connected directly to the utility grid. Unfortunately, this mode of operation limits the rotor speed to a specific rpm. Variable-speed operation is preferred in order to facilitate maximum energy capture over a wide range of wind speeds. This paper explores variable-speed operating strategies for wind turbine applications. The objectives are to maximize energy production, provide controlled start-up and reduce torque loading. This paper focuses on optimizing the energy captured by operating at maximum aerodynamic efficiency at any wind speed.