Studies On Key Technologies Of Microgrid Operation Control

With the serious energy crisis and environmental problems,the power supply system composed of a variety of distributed power supply,energy storage devices,load and control devices are well recognized to access to large power grid way in the form of micro-network,and the friendly cooperation between microgrids and large grids has become crucial.This paper focuses on the "local level coordination control layer" and "microgrids level coordination control layer" in the three levels of coordinated control of microgrid operation,including the synchronous grid connection control,the smooth switching among the operation modes and the microsources energy optimization.The main tasks are as follows:(1)From the perspective of physical mechanism,the droop control and its characters of dynamic process are derived in this paper,and the non-synchronizations of voltage magnitude,frequency and phrases before grid connection are analyzed.An improved droop control strategy was proposed,and a linear progressive approximation phase correction algorithm is added to solve the problem of non-synchronization of the microgrid and the power grid.The effectiveness of the proposed phase adjustment method is verified by both the physical experiment curve and the simulation results..(2)The control system of the inverter and its coupling problems,and the influences of line impedance on operation controls and decoupling controls are analyzed.It is proposed that the control algorithm of operation of microgrid based on nonlinear active disturbance rejection control technique.An active disturbance rejection controller was designed and the control parameters are given.This paper also simulated and compared the control effect of ADRC control strategy and PID control strategy from the "grid-connected to island","island to grid-connected","load variation",and the strong anti-interference ability of ADRC is verified.The results of the physical experiments also validate the validity and practicability of the ADRC control strategy.And the stability of the second order nonlinear active disturbance rejection controller under the definition of Lyapunov is proved in the case of the hypothesis of the perturbation.(3)A chaotic niche particle swarm optimization algorithm under the disturbing mode is proposed.The problem of local optimization in the process of multi extremum was avoided because of the disturbance thought being added to the particle swarm optimization algorithm.An operation optimization control scheme under the constraint conditions and control objectives for a given was constructed by using the improved algorithm,and realized the energy coordination among the microsources.