Research On Polymorphic Energy Routing Based On Partial Power Conversion

Efficient use of various forms of distributed energy such as photovoltaic(PV)and hydrogen energy is an important measure to cope with the polymorphic energy system transformation with green energy conservation as the goal.As a key technology in the energy internet,energy router can integrate all polymorphic energy and realize the energy regulation of each unit.Some power conversion technologies can reduce the power level required by the converter to improve the energy conversion efficiency.In this paper,based on partial power conversion(PPC)technology,polymorphic integrated energy routing system structure establishment,characteristic analysis,control strategy,scenario,mode and stability analysis,simulation and experimental verification are studied.This paper first introduces the partial power conversion technology and multi-port transformer in the conventional energy routing structure.The efficiency advantage of partial power conversion technology over full power conversion(FPC)technology in power transformers is compared and analyzed.PPC structures are established for the PV side,reversible solid oxide cell(r SOC)side,and battery side,and the principles and advantages of each structure are verified through simulation.The comprehensive use of various PPC structures and polymorphic energy is achieved by combining independent DC buses with different voltage levels and multiport converter,leading to the establishment of a polymorphic multiport integrated routing system.The characteristics of the quad active bridge(QAB)converter in the integrated routing system are analyzed and mathematical models are established.The coupling relationship in the system’s equivalent topology structure is analyzed,and the four-port structure is transformed into a three-inductor structure through circuit equivalence and parameter conversion to achieve power decoupling.Initial ripple suppression measures are applied to further optimize the integrated routing system,resulting in an optimized system.Secondly,based on the system power decoupling structure,the phase shift control of the QAB converter is performed.The operational principle of the dual active bridge(DAB)converter under single phase shift control is analyzed.In conjunction with the characteristics of each distributed energy source,controllers are established for each port of the routing system to achieve voltage/current control and maximum power transmission control at each port.The working states of the distributed energy sources are classified to analyze the power flow between modes and buses for multiple operating scenarios of the system.Furthermore,a hierarchical control architecture is established for the system under the context of energy scheduling in the energy internet,in order to establish a scenario switching strategy for the system.Next,the stability of the system is investigated,including the PPC technology and components within the power converters such as transformers and control systems.The equivalent structure and model of the system under two fault conditions,port short-circuit and device open-circuit conditions,are established for stability analysis.The current safety threshold at each port under different faults is calculated to obtain a reference value for the margin of the selected switching devices.Based on the output and response characteristics of each distributed energy source and the scenario switching strategy of the routing system,the stability of the polytypic energy is analyzed,and the system is dynamically modeled to improve the dynamic response characteristics and stability of the system.Finally,this paper establishes equivalent models for each distributed energy,designs simulation parameters,and builds an experimental platform to simulate and experimentally verify the stable operation of the overall system under the proposed control strategy and scenario switching strategy.The cost comparison and evaluation of the system are carried out,and the feasibility of the system is comprehensively analyzed.