Research on complex integrated energy planning and operation optimization

The safe and stable operation of the energy system is the top priority of the world in the industrial field. The energy integrated system optimizes the system through multiple channels and cascade utilization of energy, which greatly improves the utilization rate of energy and provides a convenient way for the development of low-carbon society. In this paper, the composite integrated energy system model is constructed through the analysis of the structure of the integrated energy system. On this basis, a coordinated optimal scheduling method for integrated energy system with multiple energy stations is proposed, which takes the system operation economy as the goal. The case simulation results show that the coordinated operation of energy stations can greatly improve the stability and economy of the hybrid integrated energy system.


Introduction
The existing literature separates optimization scheduling from the configuration optimization. Reference [1][2] carryout comprehensive modelling of electric power, natural gas and thermal system, analyses the model of energy network, and carries out energy flow analysis on this basis; Reference [3] adopts the multi-criterion partial pressure method to analyse the micro-cooling and heating power systems under different climatic conditions; In reference [4][5], a multi-user optimal configuration model with energy storage is established aiming at configuration economy. Reference [6][7][8] research on home energy efficiency management strategies based on distributed photos tatting power stations and energy storage systems.
Based on the concept of complex integrated energy, it will interconnect all kinds of new energy sources and optimize the allocation and operation of resources, to realize the complementation of integrated energy, and then to maximize the benefits in real life, compared with existing literature, considering the operation economy, environmental protection and energy saving of the scheme, in order to achieve energy allocation and operation optimization.

Introduction to the complementary coordination program for integrated energy systems
The complex integrated energy system is composed of several distributed energy stations and load zones. The "horizontal multi-purpose complementation" in the energy Internet refers to the complementary coordination among various energy resources in distributed energy stations, highlighting the "substitution". In order to improve the utilization rate of resources, the "source-network-load-storage" coordinated development concept is adopted in the process of distributed energy scheduling. Therefore, the coordinated development strategy of source-net-load-storage is put forward. Source-net-load complementary coordination: first of all, introducing demand-side response on the load side and using direct load means to reduce load tracking fan and photo voltaic output, the load cannot be reduced during the peak period of renewable energy output.

Power network model
We first assume that the rated voltage between each energy station, then the transmission loss between the two energy stations is The formula:

CHP unit model
At present, in the modeling of integrated energy system, the equivalent treatment of each energy station is carried out. As the core equipment of the integrated energy system, the CHP unit uses the load end of the natural gas system and the source end of the power generation system to cool and heat the whole energy of the system is connected.
In the formula, 1 f allocation costs for energy systems; 2 f for the comprehensive benefits of energy system operation; .e. CHP t P is the generation power and heat generation power of CHP system in the period. . .e. max j grid P , j. . max grid P is the upper limit of power line and heat transmission pipeline energy station.

(1) Energy balance constraints within energy stations
Each of the two energy stations in the regional integrated energy system needs to meet the constraints of the balance of electric energy, heat energy and cold energy. It is now expressed as formula (10)-(12).

Case study
The integrated energy system load and renewable energy processing forecast data are shown in Figure 1. Energy Station 2 is equipped with a gas boiler with limited capacity to generate heat energy at the peak of heat load.  In order to verify the economic type of energy system station coordination and optimal operation method, two ways can be set up. It can be seen from Table 1 that the energy supply cost of mode 3 is the highest, that of mode 1 is 12.6% higher than that of mode 3, and that of mode 1 is 3.6% higher than that of mode 2. Among mode 3, the purchase cost is the most, accounting for 75.8% of the total operating cost, while the purchase cost is only 13.0.

Conclusion
This paper puts forward a cooperative optimization strategy of energy station of integrated energy system with the goal of system operation economy. Through case analysis, it is verified that the coordinated optimal operation of complex integrated energy station can greatly improve the economic and environmental protection of terminal energy supply.
Science and Technology Project of State Grid Corporation of China, kjcb-2020-44. Research on key technologies of energy efficiency assessment and global optimization of composite integrated energy systems.