Development And Experimental Research Of Three-Phase Electric Spring Device

The electric spring is inspired by mechanical springs.In power system,similar to the application of mechanical springs,the electric spring device composed of power electronic devices can "buffer" the fluctuating electric quantity in the power grid.So as to alleviate the intermittent and uncertain problems brought by new energy generation to the power grid.At present,the research of electric spring is still at the stage of theoretical research,and its experimental research is mostly focused on single-phase electric spring.The experimental research of three-phase electric spring is less than single-phase electric spring.Compared with single-phase electric spring,three-phase electric spring has more advantages in voltage support and three-phase power unbalance control.Therefore,the main work of this paper will focus on the research and development of three-phase electric spring device,and provide experimental basis for the theoretical research of three-phase electric spring.The main contents of this paper are as follows:(1)Firstly,this paper systematically summarizes the research status of electric spring at home and abroad;(2)It briefly introduces the concept of electric spring,summarizes the current topological structure of electric spring,studies the working mode of electric spring,and based on the working theory of electric spring,a three-phase electric spring voltage stabilization control strategy based on PI control is proposed;(3)According to the working principle of the power spring,considering the physical constraints of the electric spring,combined with the experimental objectives such as the voltage fluctuation range of the load,the three-phase electric spring device and the main circuit parameters are designed step by step.The simulation model is built on PSCAD/EMTDC platform,and three working conditions of three-phase electric spring in capacitive mode,inductive mode and unbalanced voltage mode are simulated respectively.The results verify the rationality of the proposed control strategy and design.(4)Finally,a 380V voltage level three-phase electric spring experimental platform based on FGPA+DSP dual-chip processing controller is built to verify the correctness of the design and theory of the three-phase electric spring device.The experimental results show that the three-phase power spring device can stabilize the key load voltage in the range of(+10%)fluctuation of the grid voltage,and verify the rationality of parameter design and the correctness of its theory.For the first time,a three-phase electric spring device with a capacity of 65kVA based on a three-phase bridge topology with capacitance is designed.The DC side of the three-phase bridge circuit is a capacitor.There is no relevant report on the device's topology or the capacity of the device.The simulation and experimental results show that the control strategy of the three-phase electric spring is correct and the design method is reasonable,which provides a reference for the engineering application of the electric spring.