Zhiling Liao

Improved Particle Swarm Optimization Algorithm Based on Periodic Evolution Strategy

This paper proposed a novel improved PSO algorithm based on an periodic evolution strategy (PSO-PES). From experiments, we observe that the novel search strategy enables the improved PSO to make use of swarm’s information on velocity more effectively to generate better quality solutions iteratively when compared to exiting PSO variants. And PSO-PES significantly improves the PSO’s performance and gives the better performance than original PSO. Another attractive property of the improved PSO is that it does not introduce any complex operations to the original simple PSO framework. The only difference from the standard PSO is the best solution will update by a periodic evolution strategy. PSO-PES is also simple and easy to implement like the original PSO.

Analysis of Power Loss in Transformerless Grid Connected PV Inverter

Efficiency is becoming increasingly important in grid connected photovoltaic inverter design. Transformer in grid connected inverter system is removed to improve the efficiency of the system. Traditional power loss calculation methods often neglected ripple current effects. However, photovoltaic inverters seldom operate at the maximum rated power due to variation of irradiation. Therefore, the ripple current effects on component power loss on the light load condition should not be neglected. The chapter analyzes the working principle of a transformerless grid connected inverter in detail, and establishes a mathematical model of component power loss which includes ripple current effects. An experimental prototype is made and experiment results verify the correctness of the theoretical analysis.

Control Strategy of Grid-Connected Inverter Suppressing Grid-Voltage Background Harmonics Based on the Improved Passive Damping Method

The traditional LCL-filter third-order system grid-connected inverter may cause the resonance phenomenon without damping. Also, it will be affected by the distorted grid-voltage background harmonics. In order to overcome the problem, a new control strategy is proposed. The chapter analyzes the current waveform performance of grid-connected inverter in the condition of grid-voltage background harmonics, which derive the feed-forward function for grid-connected inverter. The disadvantages of passive damping could be well solved by damping resistor virtualization of the original system, which realizes the active damping suppression of resonance. Simulation results based on the Heric single-phase transformerless grid-connected inverter verify the correctness of the theoretical analysis.