No abstract

In this paper, a systematic control strategy has been proposed for specific problems with the various key performance indicators of the high-power photovoltaic (PV) inverter when it connects to the grid. it proposes fast and accurate variable-step-size perturbation and observation combined with power prediction as a Maximum Power Point Tracking-based (MPPT) control strategy. To meet the requirements for low voltage ride through (LVRT), it proposes a strategy for LVRT control. It adopts an active method used for anti-islanding detection of reactive power disturbance so as to realize anti-islanding detection quickly. Finally, it carries out testing on the control strategy by means of an experimental platform with a 500 kW PV inverter to prove the effectiveness of the proposed control strategy.

The paper starts from the angle of the induction motor energy loss, antis light-load energy conservation issues for induction motor, proposes a closed-loop control method of the motor power factor which is the amount of system feedback, and gives the constraint condition of the reducing voltage energy-saving. Different loads have different values of the optimal motor power factor, real-time adjusting the motor power factor to make the motor always run at the optimal power factor, and when running at light load, reducing the output voltage of the inverter, to reduce the motor copper loss and iron loss, to improve motor efficiency and power factor, to achieve reducing voltage energy-saving purposes, and to achieve the function of induction motor load following energy-saving. The experimental results show that the motor is able to maintain a high power factor operation in light load conditions, and has a good energy-saving effect.

Based on the single-phase H-H power unit topology in the novel co-phase power supply system, with the back-to-back grid-connected operation method, this paper aimed at solving the problem that in experiment, system capacity constraints caused the failure to achieve unit full power output and proposed the strategy of rectifier voltage, current double closed loop and full disturbance feed-forward control. Finally, based on the digital signal processor (DSP) and complex programmable logic device (CPLD), this study constructed a hardware platform of the power unit control system. Experimental results show that the system is stable, achieving two-way flow of energy.