Research On Distributed Hierarchical Control Of Independent Hybird Microgrid Based On Consistency Algorithm

Due to the forthcoming depletion of traditional energy and the increasingly severe environmental problems,microgrid distributed generation technology emerges and develops quickly,The renewable energy can be utilized by flexible control of distributed power sources.As an important method for controlling the distributed power distribution of microgrid,droop control is widely applied in microgrid systems.However,in the independent low-voltage microgrid system,the circuit is generally resistive,which is difficult to meet the application conditions of droop control and is affected by different impedance of the line.The effects of impedance difference make it difficult to achieve a reasonable distribution of distributed power output power.In addition,the droop control will cause the frequency and voltage deviation in the process of adjusting the power of the microgrid.This paper has carried out related research on the above problems.Firstly,based on the research of hierarchical distributed control principle of microgrid,this paper analyzes the control strategies of different types of distributed power sources in microgrid and the consistent and controllable algorithm with leading nodes to solve the problem that the distribution between the active power and reactive power for independent hybrid microgrid and the frequency and voltage deviation caused by power control,the paper establishes a distributed hierarchical control structure of independent hybrid microgrid.Then,based on the analysis of the active power and reactive power distribution mechanism of the parallel connected units of the microgrid,the conditions for proportional distribution of active power and reactive power of distributed power supply are given.The limitations of droop control in low-voltage microgrid applications and the adverse effects of different line parameters on the control system are presented.This paper proposes an improved droop control method for adaptive virtual impedance.Secondly,in order to ensure the economic operation of the microgrid system,combined with the power generation cost function of each distributed unit,a flexible and adjustable economic droop coefficient is designed by using the micro-increment rate criterion.Finally,in order to compensate for the frequency and voltage offset caused by the distributed layer control of the microgrid,a distributed two-layer frequency-voltage recovery controller for independent hybrid microgrid based on consistency algorithm is designed,and the frequency and voltage correction are introduced respectively.The item improves the distributed two-layer controller.In order to verify the effectiveness of the designed controller,the simulation is verified in different scenarios.The simulation results show that the improved droop control method based on adaptive virtual impedance in this paper can be applied to micro-network of low-voltage system,and can realize the reasonable distribution of active power and reactive power according to the minimum total cost of micro-network operation.Compared with the centralized two-layer control method,the improved distributed two-layer frequency-voltage recovery control method can better make up for the frequency and voltage deviation brought by one layer of micro-network control.In addition,it provides more accurate reference value of frequency and voltage for distributed one layer control,and active power and reactive power have been improved of the network.