The Study Of Droop Control In Low Voltage Microgrid

With the depletion of traditional fossil fuels, solar energy, wind energy, tidal energy and other new energy sources have occupied a prominent position increasingly. Due to the randomness, dispersion, diversity and other special features of renewable energy, people pay more attention to the research of distributed power generation systems. Then the concept of micro-grid has emerged. When the microgrid islanded operation, droop control is commonly used. There are two basic droop control strategies, P-V droop control and P-f droop control. The paper is focused on the P-V droop control strategy in the low voltage micro-grid.Traditional P-f droop control is widely used, and P-V droop control is rarely used. But traditional P-f droop control has a strong coupling in the low micro-grid. Therefore, the research for the feasibility P-V droop control in low micro-grid was carried out. The theoretical analysis of droop control strategy is derived, and then the stable operating conditions of P-V droop control and traditional P-f droop control were deduced in the low-voltage. And the feasibility of P-V droop control can be proved theoretically.Furthermore, in the micro-grid systerm, the voltage and frequency of the network nodes affect the working status of the loads, and on the contrary, the load characteristics also have an effect on the status of the network. So considering the load character, this paper analyzed the control performance of P-V droop control when the load changes. And the constant impedance load was chosen for the study.The performance was also compared with the traditional P-f droop control. And the simulation study was carried out. The theoretical analysis and simulation results showed that both P-V droop control and traditional P-f droop control can keep the system stable operation in the low-voltage system, and either of these two droop control has their own advantages in differenr aspects. So a specific droop control strategy was selected according to the requirements of the system.Finally, on the basis of the theoretical analysis and simulation, the control performance of P-V and P-f droop control strategy were compared. In the experiments, the three-phase inverters were controlled with a DSP TMS320F2812control systerm. The experimental results verified the correctness of theoretical analysis and simulation.