Group-Control Technology Of Modular Parallel PV Grid-Connected Inverter

Recently, due to the more and more severe energy shortage and environmental pollution, the green,clean,renewable solar power technology has been strongly supported and developed.PV inverter, the key device to the system,determines the safety,reliability and stability for operation. Compared to the traditional centralized PV inverter,the modular PV inverter would not only have higher conversion efficiency and reliability, but also could be easily maintained and extended online.Because of the varying isolation and weather, the PV inverter could not operate under the rated power at most time. Thus, the traditional single grid-connecting inverter would work in lower efficiency. Due to the changes of the weather and the insolation, PV grid-connected inverters can hardly operate at their rated-power all time. In this case, some issues, like low efficiency and poor power quality, could happen to the traditional centralized-inverters. In order to enhance the efficiency for the solar power generation, this paper introduces a high-power inverter built up by a plurality of low-power modular inverters parallel with each other, which could coordinate the parallel low-power modular inverters in operation through group-control technology and realize the current average control by introducing the droop feature in dc side for the high-power inverter. Thus, the dynamic performance and stability for the high-power inverter system could have a significant improvement. As a result, a better efficiency and power quality will be achieved while the photovoltaic power plants are operating in all the power range.A promising group controller in modular inverter would be set up to make the inverter work at MPP and adjust appropriate number of inverter starting or halting. Besides,it can check out the operating errors.MCGS monitoring software could be the human-computer interaction and realizing communication. It can control the inverting modular in group so as to meet the requirements for experiment. The monitoring software in system should fulfill displaying the data collected from the inverters, sending the parameters to inverters, and showing the error message to realizing the optimal group control. As the computer would communicate with inverter modular through the serial ports RS485. Meanwhile, the script software DrvConfig matched with configuration software was selected to program and optimize, realizing the whole control system.