Research On Optimal Operation Of Regional Integrated Energy System Considering Virtual Energy Storage

With the increasingly serious problems of environmental pollution and energy scarcity,the development of integrated energy system has become an effective means to promote the local consumption of renewable energy and realize the optimal utilization of multiple energy sources.As the scale of the energy system continues to expand under the impetus of the Energy Internet,the cloud-edge collaborative dispatching method appears better performance than the traditional centralized optimization method in dealing with the problem of multi-stakeholder and multi-energy coupling collaborative operation.This thesis has comprehensively considered the operating costs of multiple energy supply systems and the difference in response characteristics of different energy forms,and then has studied the optimal operation of integrated energy system considering virtual energy storage,aiming to adopt reasonable and effective regulation means to realize the refined control of various energy resources in the system step by step,along with regional autonomous optimization.The following research work has been specifically carried out as follows:1)According to the characteristics of "horizontal multi-source complementation and vertical multi-layer coordination",the multi-level coordinated control architecture which takes the energy management cloud platform as the centralized control layer,along with the edge controller for each region as the distributed coordination layer has been presented.Based on the“source-network-load-storage” structure,the operating principles of energy production,conversion and storage equipment in the integrated energy system are discussed successively and their specific mathematical models are established as follows.Taking into account the diversity and complexity of the equipment in the integrated energy system,according to the principle of abstract equivalence,the district heating network and the flexible load in the system are regarded as virtual energy storage equipment,and the indices of charging and discharging power,charging and discharging time and virtual charge state are considered to conduct virtual energy storage modeling,so that this kind of flexible resources can form the generalized energy storage with conventional energy storage equipment to participate in the optimal scheduling of integrated energy systems,which has laid a model foundation for the subsequent research on energy optimization of the integrated energy system.2)Comprehensively considering the functions and dynamic response characteristics of various scheduling resources,taking virtual energy storage as flexible scheduling resources,a regional integrated energy system coordinated scheduling framework for day-ahead and the day-in-day stages are proposed.Based on the long-,mid-,and short-term forecast results of renewable energy generation and uncontrollable load,taking system operation economy and safety as the optimization goal,comprehensively considering various energy power balance constraints and operating characteristics of controllable devices,the thermo-electric coupling complementary characteristics are utilized and the regional heating network,controllable cooling and heating loads and transferable loads are included in schedulable resources in the day-ahead stage to perform coordinated optimal dispatch of integrated energy.Further,the rapid response characteristics of some power equipment are used and the interruptible load and DLC load are included in the schedulable resource in the intra-day stage to act on the short-term electric power fluctuation in the system.The simulation results show that the integrated energy system energy optimization model combined with virtual energy storage can effectively improve the flexibility of system regulation while reducing computational complexity.3)In order to give full play to the time and space complementary advantages of the energy resources among regions,comprehensively considering the regional interests and their adjustment capabilities of participating in coordination,a cloud-edge coordinated dispatching method for integrated energy system in real-time stage has been formulated.Based on the latest prediction results of renewable energy and electric load in various regions,an optimization model that meets the overall economic and safety goals of the system is established in the energy management cloud platform,and a refined control model which is based on the scheduling results of intra-day optimization is established in the edge controllers using model predictive control method.Further,both of these models have been integrated into a form that can be solved by a distributed optimization algorithm,and the coordination of regional selfinterest and the overall benefit has been realized after a limited iteration process.The simulation results show that through the transmission power coordination among regions and auxiliary calls for energy storage and DLC load can effectively smooth the real-time fluctuation of renewable energy output and electric load demand,and improve the robustness and effectiveness of the overall operation control.