Research On Stability Analysis And Optimal Control Strategy Of Micro Combined Power Supply System

Micro Combined Power Supply System(MCPSS)is a portable field-portable optical storage integrated power generation device composed of portable photovoltaic panels,hybrid energy storage units,and power conversion units.It is used to overcome the shortcomings of traditional power supply methods,such as narrow energy source channels,weak power supply continuity,and low mass energy density.It can be widely used in field reconnaissance,training,or combat operations by individual soldiers or teams.In order to deeply analyze the influence of micro-source characteristics such as photovoltaic and energy storage,system operation mode and stability control strategy on the stable operation boundary of MCPSS,this thesis carried out in-depth theoretical analysis and simulation verification from the aspects of system model establishment,mixed potential function stability boundary determination,MPPT control algorithm optimization,virtual motor control and system joint simulation verification.The research work is summarized as follows :Firstly,the working characteristics of each component of the system are analyzed and expounded in detail,and the nonlinear mathematical model of MCPSS is established.Combined with the overall topology and typical application scenarios of MCPSS,the working state of each power supply unit in typical mode is analyzed,and the mathematical models of photovoltaic power generation subsystem,hybrid energy storage system and power conversion unit are established.Through simulation experiments,the working characteristics of each subsystem are analyzed in depth,which lays a model foundation for the subsequent research on MCPSS stability analysis and optimal control strategy.Then,based on the mixed potential function theory,the large signal stability analysis of MCPSS is carried out,and the stable operation boundary expression under different operation modes is given.By establishing the mathematical models of optical-storage-power supply mode,hybrid energy storage power supply mode and charging maintenance mode,based on the theory of hybrid potential function,the stable operation boundary value of load power is deduced and calculated.The load capacity of DC bus under different working modes is verified by simulation,which proves the correctness of the mathematical expression of the stable operation boundary.Secondly,the particle swarm MPPT algorithm and the additional differential virtual DC motor stability control strategy are proposed,and the effectiveness of the method is verified by simulation.Aiming at the photovoltaic power generation subsystem,a nonlinear mutation improved ring particle swarm optimization(MIRPSO)MPPT algorithm under partial shadow condition is proposed,which effectively solves the problems of severe fluctuation and poor convergence effect of maximum power point tracking,improves the efficiency of solar power generation and reduces the power loss.For the hybrid energy storage system,a droop control method with additional differential virtual DC motor link is proposed.Under the condition of large load disturbance,the unbalanced power can be reasonably distributed,the dynamic response speed is accelerated,the DC bus voltage fluctuation range and steady-state error are reduced,and the system stability is improved.Finally,based on the stability control strategy given in the thesis,the simulation of MCPSS overall joint stable operation control is carried out,and the dynamic characteristics of the overall operation of the system under three typical operating modes are simulated,which further proves the effectiveness of the proposed control method for expanding the load power boundary of the system.