Research On Topology And Control Of Voltage-Type DC Electric Spring

Under the background of limited global fossil energy resources and long-term unsustainability,my country has put forward the requirements of "carbon peaking" and "carbon neutrality",and the new energy generation system(Renewable Energy Generation,REG)gradually transitioned from the supplementary power source to the main power source However,its inherent intermittent and unstable characteristics and the imbalance of instantaneous power lead to the widespread abandonment of light and wind in large-scale new energy power generation grids,so traditional energy storage devices are widely used in REGs.Direct current clectric springs(DCES),as a new way to solve the power quality problem caused by the unstable output of photovoltaic and wind power integrated into the DC microgrid,has the advantages of flexible configuration and small size.The basic principle of DCES is to transfer the REG energy fluctuations to the non-critical load(NCL)by controlling,and maintain the critical load(CL)voltage stability.Single-Phase-Shifting(SPS)control for TAB converters controls the flow of energy between ports by changing the phase-shift angle between ports.The control strategy is simple,but there are problems such as large primary-side return power,low efficiency,and small Zero Voltage Switching(ZVS)interval at high gain.Based on the existing DCES-3 topology,this paper proposes a simple extended phase-shift control strategy.The control strategy realizes the optimization of the power-side return power on the basis of Extended-Phase-Shifting(EPS),and determines the optimal phase-shift angle in the power-side bridge to ensure that all switching devices achieve ZVS.Finally,the correctness and effectiveness of the proposed control strategy are verified by the simulation model and experimental results.Aiming at the problems that the "spring" of the DCES-3 topology is not obvious,the voltage of the port where the NCL is located is relatively large,the scene modification and production costs are high,and the overall control is not realized.This paper proposes an improved DCES-3 topology.The topology working mode is analyzed and a three-dimensional decoupling control strategy based on SPS control is proposed.The strategy realizes energy distribution among ports through SPS control.The decoupling control realizes the decoupling between the key load voltage,input power,battery current and other input quantities and the phase shift angle,buck/boost converter duty cycle and other control quantities,and obtains a better control effect.Finally,the correctness and effectiveness of the proposed DCES topology and its control strategy are verified through simulation and experiments,and the proposed DCES improved topology and its control advantages are summarized.Finally,according to the photovoltaic cell simulation and the proposed DCES-3 improved topology and its control strategy,this paper introduces the specific application scenarios of the topology in the rooftop photovoltaic power generation system.The software design and hardware design process of the control platform based on TMS 32028335 in the process of platform construction are described.It provides a reference for the design and application of subsequent DCES in new energy power generation scenarios.