Research On Distributed Hierarchical Control Strategy Of Island Microgrid Based On MAS

Micro-grid is a small power generation and distribution system used to flexibly and efficiently solve a large number of different types of DG grid-connected or island operation problems.It consists of distributed generation(DG),energy storage devices,and energy conversion device,load,protection and monitoring device,etc.Microgrid has two operating modes: grid-connected mode and island mode.The island mode microgrid can solve the problem of insufficient power supply in remote areas such as islands and border defenses.However,the island microgrid lacks the support of the main grid,its operational stability and power supply quality cannot be guaranteed,and it needs its own DG and other controllable units to maintain it.This article takes the island microgrid as the research object,considers the communication delay problem in the actual operating environment,and uses the multi-agent system(MAS)delay distributed algorithm in the microgrid hierarchical control.The control strategy and the optimized distributed control algorithm make the system parameters run in the optimal state to ensure the active power balance,frequency stability and operating economy of the island microgrid during operation.Generally speaking,each DG needs to be connected to the grid through an inverter.Therefore,the article firstly models and analyzes the three control methods of distributed power inverters: V/f,PQ and Droop control,and introduces in detail the hierarchical control architecture of island microgrid and the functions and control methods of each layer of control.Secondly,the multi-agent system and distributed consensus algorithm used in the second-level control and the third-level control are introduced in detail,and the convergence performance of the improved time-delay consensus algorithm is simulated and analyzed.Aiming at the problem of primary control frequency deviation and power allocation,a secondary frequency modulation control model is established and corresponding control strategies are formulated.The discrete time delay consistency algorithm is used in the secondary control strategy to ensure the rapid adjustment of frequency and active power.Using event trigger mechanism,when the system fails or the load is switched on and off,the control strategy is triggered to make the frequency and power reach a new equilibrium state.There are many control objects of the third-level control.The article mainly studies the operating cost economy of microgrid by optimizing the control algorithm and considering the actual communication delay.Aiming at the optimal economic dispatch problem of island microgrid,a continuous distributed algorithm update rule considering random delay is proposed to ensure the lowest operating cost of microgrid through incremental cost consistency.Design the calculation strategy considering the active power constraints of the generator set,and verify its effectiveness through simulation.