Energy management and power flow of decoupled generation system for power conditioning of renewable energy sources

Paper presents decoupled variable (adjustable) speed generation system and its application in renewable energy generation. The decoupled generation system consists of internal combustion engine, permanent magnet generator and AC/AC converter. Performance of single decoupled generation set are discussed supported by results of laboratory tests. The variable speed system provides high quality voltage in wide speed range when the step of load is low. However, when the step load is significant the voltage drop is not acceptable. Therefore to provide high quality produced voltage an additional energy storage, made from supercapacitor and bidirectional DC/DC converter, is applied. Such system performs very stiff voltage in any load condition. Integration of renewable wind energy system is provided via DC link of the variable speed decoupled autonomous generation system. The priority of the power draw is from the wind source. This is assured by a method of three reference signals for the DC link voltage. Speed control of the driving engine in region of low specific fuel consumption results in high efficiency conditioning of the unstable (wild) variable renewable energy source.