Bie Chaohong et al. from Xi'an Jiaotong University: Research on "Source-Grid-Load" Planning of Energy Internet

The planning of regional multi-energy systems requires not only the site selection and sizing of CHP units, energy storage equipment and other devices, but also the planning of the corresponding electricity, gas and heat distribution networks. Therefore, it is necessary to first establish a power conversion model for CHP units and energy storage equipment. The energy hub model can be used to make different configurations according to different needs. Secondly, using CHP units and other devices as coupling elements, and based on the optimal power flow of electricity, gas and heat coupling, different operating scenarios are set and different planning models are established to adapt to actual conditions.

The planning of energy microgrids is mainly about the selection and sizing of combined cooling, heating and power equipment. Based on the forecast of cooling, heating and electricity loads of energy microgrids, according to the changes in energy prices and the price-based demand-side response that users may participate in, several different typical operation modes are set, and the selection and sizing of equipment are carried out based on the optimal operation of the system. When multiple energy microgrids are interconnected and coordinated, the coordination and mutual assistance of multi-energy routers also need to be considered.

7. In the research on energy Internet planning, what key issues need to be addressed?

1) Analyze and simulate the output uncertainty of renewable energy units and the uncertainty of users’ demand for different energy sources in the planning model, such as wind power output simulation and user participation in price-based demand-side response simulation.

2) Study the impact of time constants of different energy systems on energy conversion of coupled multi-energy systems. In the energy Internet, the transient processes of different energy systems last for different durations. Electric energy requires instantaneous balance, while the transient processes of gas and heat systems are relatively slow, measured in minutes and hours.

3) In the planning model of the energy internet, energy supply reliability is an important constraint. It is necessary to first establish a reliability model for energy production, conversion, and storage equipment in the energy internet, and based on this, establish a reliability assessment system for the electric-gas-heat coupling system, so as to add reliability constraints or reliability verification iterative submodules to the planning model.

4) The steady-state gas flow model of natural gas and the steady-state thermal-hydraulic model of the thermal network have non-convex nonlinearities, which makes the planning model of the electric-gas-heat coupling system a large-scale mixed integer nonlinear programming model, which is very difficult to solve. Therefore, it is necessary to use linearization, second-order cone relaxation and other methods to deal with non-convex constraints, and design a reasonable optimization algorithm to solve the optimization planning problem of large-scale systems.

5) Energy prices will have a significant impact on the results of the planning model. There are various participants in different systems and links in the energy Internet. The different market participation methods and different decisions of various participants will cause uncertainty in energy production and consumption. Therefore, it is necessary to reasonably model and analyze energy price factors to deal with the uncertainty factors caused by different energy prices.

Citation Information

Bie Chaohong, Wang Xu, Hu Yuan. Review and Prospect of Energy Internet Planning Research[J]. Proceedings of the CSEE, 2017, 37(22): 6445-6462.

Bie Zhaohong, Wang Xu, Hu Yuan． Review and prospect of planning of energy internet[J]. Proceedings of the CSEE, 2017, 37(22): 6445-6462 (in Chinese).

About the Team

The Energy Internet Research Team of Xi'an Jiaotong University is led by Academician Guan Xiaohong and Professor Bie Chaohong. It relies on the Shaanxi Provincial Key Laboratory of Smart Grid and the Ministry of Education's Key Laboratory of Intelligent Network and Network Security. It is a multidisciplinary cross-disciplinary research team composed of teachers from multiple disciplines such as electrical engineering, systems engineering, and energy and power.

The research team led the 2016 National Key R&D Program "Smart Grid Technology and Equipment" key project "Basic Theory of Planning, Operation and Trading of Energy Internet". Professor Bie Chaohong is the project leader, Xi'an Jiaotong University is the project leader, Tsinghua University, Institute of Mathematics and Systems Science of the Chinese Academy of Sciences, Northeastern University, Shenzhen Institute of the University of Hong Kong, Shanghai Jiaotong University, China Electric Power Research Institute and Northwest Branch of State Grid Corporation of China are participating units. The project focuses on energy Internet system modeling and simulation, energy Internet collaborative planning, market design and mechanism analysis, random dynamic optimization scheduling, resource allocation and bidding of multi-energy systems, etc., aiming to form the basic theory of energy Internet planning, operation and trading, establish a simulation platform, finely simulate the production, transmission, storage, conversion and consumption of various energy sources, and promote the application of energy Internet technology. At present, the project is progressing smoothly and has achieved phased results in three aspects: modeling and analysis of information-physical fusion systems of energy Internet, system planning and trading mechanism design, and coordinated planning of energy Internet.