Research On Coordinated Optimization Control Of Isolated Microgrid Cluster With Single-Phase/Three-Phase Hybrid Architecture

In the context of the energy transformation strategy,microgrid technology is gradually scaling up.Multiple adjacent microgrids in a certain area on the user side are electrically connected to form a microgrid cluster system,which can achieve a wider range of resource optimization,promote distributed energy consumption and enhance power supply reliability.Isolated microgrid clusters with single-phase/three-phase hybrid architecture have broad application prospects under the scenarios of main power grid failure / maintenance,or in remote or island areas where power grids are weak.The methodology to make full use of the flexibility of microgrid cluster system operating mode and "source-load-storage" resources is the key to ensuring the safe,stable and efficient operation of the isolated single and three phase hybrid microgrid cluster.Therefore,the research on the collaborative optimization control technology of isolated single and three phase hybrid microgrid cluster in this paper is carried out.The main research contents are as follows:(1)Based on the analysis of the grid structure and control architecture of the isolated microgrid cluster system with single-phase/three-phase hybrid architecture,the in-depth analysis of the three-phase imbalance problem has been carried out,an effective way to achieve three-phase imbalance adjustment with flexible control strategies has been made clear.In view of the characteristics of out-of-phase electrical interconnections,a panoramic topology analysis method combining generalized Boolean operations is proposed to lay the foundation for the study of collaborative optimization control strategies.(2)Aiming at the decentralized autonomous real-time control of isolated microgrid cluster system with single-phase/three-phase hybrid architecture,a real-time control strategy based on model predictive control is proposed.The proposed strategy is based on a hierarchical control architecture,taking into account the three-phase imbalance,and taking the minimum deviation between the real-time line power and a given base value as the control target.A multi-input,multi-disturbance,multi-variable dynamic prediction model is constructed,and feedback correction is introduced to correct prediction error and achieve rolling limited time domain closed-loop optimization.Through example simulation,the proposed strategy can achieve real-time smoothing of source-load output fluctuations through decentralized autonomy,and can track real-time line power,verifying its effectiveness and robustness.(3)Based on the MPC-based decentralized real-time control and the hierarchical control architecture,a multi-timescale hierarchical control strategy for isolated microgrid cluster system with single-phase/three-phase hybrid architecture is proposed,including minute-level centralized coordinated control and hour-level dynamic isolated mode switching control.Minute-level centralized coordinated control considers the decentralized and real-time controlled restoration of photovoltaic energy curtailment and load-shearing measures.Under the constraint of three-phase imbalance,multi-objective mixed integer non-linear programming is used to achieve centralized coordination and optimization of the source and storage resources of the system.The hour-level dynamic isolated mode switching is to achieve the optimal overall resource allocation of the microgrid cluster system through the optimal decision and execution of the partition interconnection combination scheme.It is verified by a case study that the proposed strategy can cooperate with decentralized real-time control to realize multi timescale hierarchical control of isolated microgrid cluster system with single-phase/three-phase hybrid architecture,which is beneficial to the safe and efficient operation of isolated systems.(4)Aiming at the mainstream hierarchical control architecture in microgrid cluster research,a multi-process simulation platform that considers individual independence and information interaction between processes is designed.The platform is oriented to multiple control subjects,with the design principle of "one controller and one process",adapted to each controller and runs the control algorithm relatively independently,and the information interaction between multiple processes supports multiple types of specific file transfer protocols.The effectiveness and practicability of the proposed scheme is verified by case studies,which is helpful to reduce the difficulty of developing and verifying the control algorithm in the complex simulation scenario of isolated single and three phase hybrid microgrid clusters.