Based On The Droop Control Microgrid Inverters Control System Research

As the failure of non-renewable energy and ecological environment problems prominent increasingly, countries around the world are seeking to develop clean, renewable energy to ease energy crisis, and improving the power generation technology. In recent years, the distributed power generation technology has been focused gradually, it can generate energy independently and provide power supply for the loads paralleling with the power grid. But the distributed generation has many disadvantages, so microgrid has been put forward. It can not only solve the problems between the distributed generation and electric power system, but also improving the power supply reliability and expanding capacity of power supply system. It has been became one of the important chooses for the future intelligent and sustainable power system gradually.The problems of static frequency, voltage secondary control and power distribution of the droop control is analyzed and studied in this paper based on the traditional P-f/Q-V droop control microgrid.First of all, the parallel inverter power transmission characteristics and the traditional droop control theory are analyzed. In islanding operation mode, according to the power quality problems and the inverter power allocation problem, the analysis of voltage and frequency stability and power distribution conditions of microgrid inverters are researched in detail.Secondly, a novel approach to conceive the secondary control in droop controlled microgrids is presented according to the problems of power quality and the inverter power allocation of traditional droop control. Compared with the conventional approach based on restoring the frequency and amplitude deviations produced by the local droop controllers by using an MG central controller, an improved approach is used in order to implement a distributed secondary control. The output voltage amplitude, frequency and the reactive power of each inverter are restored by PI controller. The proposed approach is not only able to restore frequency and voltage of the microgrids but also ensures reactive power sharing. Simulation results are presented to show the feasibility of the distributed secondary control under different conditions.Finally, set up two inverters paralleled experiment platform based on the analysis of secondary control based on TMS320F28335 DSP simulator. The control methods adopted in this paper are established on the platform in the conditions of line impedence and varies of capacity of inverters are completed to validate the superiority of the control strategy in the frequency and voltage regulation aspects.