Ge Yangyang

Optimal placement for hybrid energy in micro-grid

Reasonable control of multiple energy forms for load power supply can effectively improve economy and reliability of micro-grid(MG) operation, however, up till now, these two problems of siting hybrid energy systems(HEMS) and scheduling them have been separately solved. In order to bring its flexible power supply capacity into fully play, this paper put forward an algorithm to optimally solve the problem of allocation and schedule of multiple hybrid photovoltaic (PV)-diesel distributed generation (DG) in distribution systems. Firstly, an energy control method of HEMS was present to improve efficiency and flexibility of MG operation; Secondly, an optimization problem was formulated considering not only to reduce the total investment, operation maintenance cost, network loss caused by imported power from the transmission grid, and un-served load in case of emergency, but also to maximize the excess generated power by the HEMS that may be injected into the distribution network.; Finally, an improved artificial bee colony (ABC)based on particle swarm optimization(PSO) was put forward to increase convergence speed. Simulation results based on IEEE - 33 and PG&E - 69 systems show that the presented control method can improve the economy of MG operation and reliability significantly.

New reactive islanding detected method for micro-grid

Islanding detection is an important technique for micro-grid connected/isolated control. Traditional passive island detection reliability is bad, while active method have negative influence on power quality, so a new method based on chaotic property was proposed. The main reasons of chaos phenomenon during micro-grid conversion process in both connected/isolated operation modes are studied in this paper. Chaos theory is applied to reconstruct the phase space of voltage waveform in the micro-grid conversion process. At the same time, the maximum Lyapunov exponents of the voltage waveform are extracted. The results prove that typical chaos phenomenon occurs during the conversion process. And finally, the simulations of micro-grid isolated detection are carried out in the platform of RTLAB, proved the islanding detection is effective based on the chaotic characteristics. Through introducing the chaos characteristics of connected/isolated micro-grid, blind areas of the island detection can be decreased, improve the accuracy and reliability of the island detection.