Multi-energy complementary integrated energy management under energy internet

China Energy Storage Network: It can be said that 2016 and 2017 were the "conceptual years" of the energy Internet. At that time, everyone was still discussing "what is the energy Internet", "why do we need to do the energy Internet", and "what the energy Internet might look like". However, 2018 has entered the "implementation year" of the energy Internet, and everyone is discussing in depth how to do it. The National Energy Administration and the Ministry of Science and Technology have many supporting projects and a large amount of capital investment, such as the first batch of "Internet +" smart energy (energy Internet) demonstration projects announced by the National Energy Administration in 2018.

Just recently, the 2018 Global Energy Internet Conference was grandly held in Beijing. More than 800 industry leaders from more than 30 countries and regions around the world gathered together to exchange ideas, share results and discuss the development of the global energy Internet around the conference theme of "Global Energy Internet - From Chinese Initiative to World Action".

It can be said that everyone is looking forward to realizing energy interconnection and expecting the energy Internet to bring new changes to human life. At the "Made in China 2025 Summit Forum" at the end of 2017, Mr. Zhang Bin, Vice President of Hanergy Group, also expressed his understanding of the future energy Internet in the "Roundtable Dialogue - Manufacturing Renaissance: Dialogue between China and the World".

The development of energy internet has raised many new issues, new viewpoints and key technologies. With the deepening of research, regional energy internet has been proposed. How to define regional energy internet: If energy internet is regarded as a multi-energy information fusion "wide area network" built with the concept of Internet, then regional energy can be regarded as a "local area network" correspondingly, called "regional energy network", which exchanges information and settles energy with the "wide area network" externally, and provides energy management and services to regional users internally.

Regional Energy Network

The regional energy network is the basis for the analysis of multi-energy systems and the concrete embodiment of the characteristics of multi-energy systems. From a functional perspective, the multi-energy system can organically integrate various forms of energy and allocate and adjust them according to factors such as price and environmental impact; from the perspective of energy services, the various needs of users are statistically considered, and the purpose of peak shaving and valley filling and reasonable energy use is achieved through reasonable scheduling; from the perspective of energy networks, the development of various energy technologies is promoted through collaborative analysis of electrical networks, natural gas networks, heat networks and other networks. The region can be as large as a city, town, or community, or as small as an industrial park, large enterprise, or building. It generally covers integrated power supply, gas supply, heating, hydrogen supply, and electrified transportation energy systems, as well as related communication and information infrastructure. Its basic characteristics are that it should have the generation, transmission, conversion, storage, and consumption of energy. In this regional network where multiple energy sources interact and merge, the carriers of information include "power flow", "natural gas flow", "information flow", and "material flow". Due to its relatively small scale, the regional energy network can be led by the government, energy companies, and large industrial enterprises to build and implement it, and it has stronger practical value. The regional energy network is part of the energy internet, involving multiple energy links with different forms and characteristics. It includes both energy links that are easy to control and energy links that are intermittent and difficult to control; it includes both energy that is difficult to store in large capacity and energy that is easy to store and transfer; there is both coordinated supply at the energy generation end and coordinated optimization at the energy consumption end.

Main features of regional energy internet

Compared with the cross-regional backbone energy Internet, the regional energy Internet takes various industrial enterprises and residents in the local area as user groups, collects information data on energy production, consumption, transmission, storage, etc., and meets the load needs of users in the domain by relying on data analysis, energy coordination and optimization scheduling mechanisms. Correspondingly, as a link between energy Internets in different regions, the cross-regional energy Internet realizes the long-distance transmission of energy between regions through large-scale power transmission, gas transmission and other system backbone networks, ensures the safe and stable operation of energy Internets in various regions within the coverage area, and provides energy external interfaces when energy overflows and gaps occur in regional Internets. In order to adapt to the energy supply and demand pattern in the local area, on the basis of fully absorbing the excellent experience of the Internet development process, the regional energy Internet has formed some characteristics that are different from the cross-regional energy Internet.

First, multi-energy complementation

In order to meet the complex user load requirements in the region, a large number of distributed energy facilities are deployed within the scope of the regional energy Internet, covering distributed CCHP, CHP, photovoltaic power generation, solar thermal collection, hydrogen production stations, ground source heat pumps and other forms, forming a composite supply system of multiple energy forms such as electricity, heat, cold, and gas, effectively realizing the cascade utilization of energy. At the same time, the regional energy Internet provides a plug-and-play standard interface for the access of various distributed energy sources, but this also puts forward higher requirements for the optimization and control of the energy Internet. To this end, technologies that promote multi-energy integration, such as coordinated planning between gas and electricity, P2G technology, V2G technology, and fuel cell technology, will play a more important role in the future.

Second, two-way interaction

The regional energy Internet will break the existing source-grid-load energy flow model and form a free, bidirectional and controllable multi-terminal energy flow model. Distributed energy routers will make it possible to interconnect energy at any node in the region. The setting of energy conversion stations or energy hubs will break down the industry barriers between the original heating companies, power companies and gas companies. Residents equipped with distributed power generation equipment are expected to participate in the energy supply of the energy Internet together with other energy suppliers. In the future, with the rapid development of the electric vehicle industry, the transportation network with smart electric vehicles as the main body will also be integrated into the existing energy Internet model.

Third, full autonomy

Different from the traditional energy utilization pattern, the regional energy Internet makes full use of various energy resources in the region, builds a self-sufficient energy system in the region, fully absorbs the distributed energy within the region, and realizes the efficient use of various energy facilities. At the same time, as a basic component of the backbone energy Internet, the regional energy Internet maintains a two-way controllable energy flow form with the backbone energy network, and uses the large backbone energy network to carry out two-way exchange of energy and information with other regional energy Internets.

Based on the above characteristics, the main feature of regional energy Internet is to use the "Internet +" thinking to reset the energy network needs, achieve a high degree of integration of energy and information, and promote the construction of energy network information infrastructure. By introducing online trading platforms, big data processing and other technologies, the energy Internet will fully tap into a large amount of information such as energy production, transmission, consumption, conversion, storage, etc., and guide energy production and scheduling through information mining technologies such as energy demand forecasting and demand-side response.

How to realize the conceptual advantages of regional energy internet? Professor Sun Hongbin of Tsinghua University systematically proposed: multi-energy complementary integrated energy management for regional energy internet. When I visited Professor Sun at Tsinghua University in 2015, he mentioned this research. At the National Energy Internet Conference in December 2017, Professor Sun formally shared and discussed this research result.

Optimal control problem for maximizing benefits

How to maximize the benefits under the premise of safe energy supply through "multi-energy complementation, source-grid-load coordination" is a focus issue that experts are very concerned about in the implementation of energy Internet demonstration projects. This is not easy to achieve. From a technical perspective, this focus issue can be attributed to the optimal control problem of a complex multi-energy flow network. This optimal control problem is to pursue the maximization of benefits, benefit = income-cost, and the constraint premise is safe energy supply. The income here includes the sale of energy and services, and the expenses include the purchase of energy and services. The means of optimization are distributed in various links such as cold, heat, gas, electricity, water, transportation, source, network, load, and storage. Constraints include supply and demand balance, physical scope of operation, and energy supply safety. This focus issue is ultimately achieved through a system called the multi-energy complementary integrated energy management system (Integrated Energy Management System), referred to as IEMS.