Polaris Energy Storage Network News: It can be said that 2016 and 2017 are the “concept years” of the energy internet. At that time, everyone was still discussing “what is the energy internet”, “why should the energy internet”, and “what might the energy internet grow?” Look”. However, 2018 has entered the “landing 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 support projects and large amounts of capital investment, such as the first batch of “Internet+” smart energy (energy Internet) demonstration projects announced by the National Energy Administration in 2018.
Polaris Energy Storage Network News: It can be said that 2016 and 2017 are the “concept years” of the energy internet. At that time, everyone was still discussing “what is the energy internet”, “why should the energy internet”, and “what might the energy internet grow?” Look”. However, 2018 has entered the “landing 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 support projects and large amounts of capital investment. For example, the first batch of “Internet+” smart energy (energy Internet) demonstration projects announced by the National Energy Administration in 2018.

Not long ago, the 2018 Global Energy Internet Conference was held in Beijing. More than 800 industry leaders from more than 30 countries and regions around the world gathered together to focus on the theme of the “Global Energy Internet-From China Initiative to World Action”. Exchange ideas, share results, and discuss global energy Internet development plans.

It can be said that everyone is very much looking forward to the realization of energy interconnection, and the energy internet is expected 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 “Round Table Dialogue-Manufacturing Revival: Dialogue between China and the World”.

The development of the energy internet has raised many new questions, new ideas and key technologies. With the deepening of research, the regional energy internet has been proposed by everyone. How to define the regional energy internet: If the energy internet is regarded as built on the Internet concept Energy information fusion “Wide Area Network” can correspond to regional energy as a “local area network”, called “regional energy network”, which exchanges information and energy settlement with the “Wide Area Network” externally, provides energy management and service.

District Energy Network

The regional energy grid is the basis of multi-energy system analysis and the concrete manifestation of the characteristics of multi-energy systems. From a functional point of view, a multi-energy system can organically integrate various forms of energy, and adjust the distribution according to factors such as price and environmental impact; from the perspective of energy services, the user’s multiple needs are statistically considered and rationally dispatched To achieve the purpose of peak-shaving and valley-filling, and reasonable energy use; from the perspective of energy networks, through the collaborative analysis of electrical networks, natural gas networks, heat networks, and other networks, promote the development of multiple energy technologies. The area can be as large as a city, town, community, as small as an industrial park, large enterprise, building, which generally covers integrated energy systems such as power supply, gas supply, heating, hydrogen supply, and electrified transportation, as well as related communication and information foundations. The basic feature of a facility is that it should have the links of energy generation, transmission, conversion, storage, and consumption. In this regional network of multiple energy integration, the carriers of information include “electricity flow”, “natural gas flow”, and “information”. Flow”, “material flow”, etc. Due to its relatively small size, the regional energy network can be led and constructed and implemented by the government, energy companies and large industrial enterprises, and has stronger practical value. The regional energy network is a part of the energy internet, which involves multiple energy links and has different forms and characteristics. It includes both easy-to-control energy links and intermittent and difficult-to-control energy links; it also contains energy that is difficult to store in large capacity , It also contains energy that is easy to store and transfer; there is both a coordinated supply at the energy generation end and a coordinated optimization at the energy consumption end.

Main features of regional energy internet

Compared with the cross-regional main energy internet, the regional energy internet uses various types of industrial enterprises and residents in a local area as the user group. By collecting energy production, consumption, transmission, storage and other information data, by means of data analysis, energy coordination and optimization The scheduling mechanism meets the load demands of users in the domain. Corresponding to this, the cross-regional energy Internet serves as the link between different regions’ energy Internet. Through large-scale power transmission, gas transmission and other system backbone networks, long-distance energy transmission between regions can be achieved, ensuring the safety and stability of the energy Internet in each region within the coverage area. Operate to provide energy external interfaces when regional Internet overflows and gaps occur. In order to adapt to the energy supply and demand pattern in local regions, 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.

One is multi-functional complementary

In order to meet the complex user load demand in the region, a large number of distributed energy facilities are deployed within the scope of the regional energy Internet, covering distributed CCHP, combined heat and power CHP, photovoltaic power generation, solar heat collection, hydrogen production stations, ground A variety of forms such as source heat pumps constitute a composite supply system of various energy forms such as electricity collection, heat, cooling, and gas, which can effectively realize the cascade utilization of energy. At the same time, the regional energy internet provides plug-and-play standard interfaces for various types of distributed energy access, but this also puts forward higher requirements for the optimization and control of the energy internet. For this reason, gas-electricity coordination planning, P2G technology, V2G technology, and fuel cell technology, which promote the integration of multi-energy, will play a more important role in the future.

The second is two-way interaction

The regional energy internet will break the existing source-net-dutch energy flow model and form a free, bidirectional and controllable multi-end energy flow model. Distributed energy routers will enable the interconnection of energy at any node in the area. The installation of energy conversion stations or energy hubs will break the industry barriers between the original heating companies, power companies and gas companies, and residents equipped with distributed power generation equipment are expected to participate in the energy supply of the energy Internet together with other energy providers. 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.

Three is 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 and the backbone energy network maintain a two-way controllable form of energy flow, with the help of the large backbone energy network and other regional energy Internet for two-way exchange of energy and information.

Based on the above characteristics, the main feature of the regional energy Internet is to use “Internet +” thinking to reset the energy network needs, to achieve a high degree of integration of energy and information, and to promote the construction of energy network information infrastructure. Through the introduction of technologies such as online trading platforms and big data processing, Energy Internet will fully mine a large amount of information such as energy production, transmission, consumption, conversion, and storage, 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 the regional energy internet, Professor Sun Hongbin of Tsinghua University systematically proposed: multi-energy complementary comprehensive energy management for the regional energy internet. When the editor visited Professor Sun at Tsinghua University in 2015, he mentioned the research. At the National Energy Internet Conference in December 2017, Professor Sun officially shared and discussed the research results.

The optimal control problem in pursuit of maximizing benefits

How to maximize the benefits under the premise of safe energy supply through “multiple energy complementation and source-network charge coordination” is a focus issue that experts are very concerned about in the implementation of the energy internet demonstration project. This is not easy to achieve. From a technical perspective, this focus problem can be attributed to the optimal control of a complex multi-energy flow network. This optimal control problem is to pursue the maximization of benefit, benefit=income-expense, and the constraint premise is safe energy supply. The income here includes sales of energy and services, and the cost includes purchasing energy and services. The optimized methods are distributed in cold, hot, gas, electricity, water, transportation, source, network, charge, storage and other links. Constraints include the balance between supply and demand, the physical range of operation, and safety of energy supply. This focus problem is finally realized by a system, which is called Integrated Energy Management System (IEMS).

History of EMS

IEMS can be considered as the fourth generation energy management system (Energy Management System, EMS). EMS is a computer decision-making system for online analysis, optimization and control applied in the power grid dispatch control center. It is the nerve center and dispatch command headquarters of the power grid operation, and the core of the wisdom of the large power grid. Professor Sun’s research group has been studying EMS for more than 30 years. First, let’s review the history of EMS.

The first generation of EMS appeared before 1969 and was called the initial EMS. This EMS only includes SCADA for power supply, but only collects the data. There is no real-time network analysis, optimization, and collaborative control. Network analysis and optimization mainly rely on offline calculations, and belong to empirical scheduling. The current park management must not stop at the level of empirical scheduling, but needs lean management to improve core competitiveness.

The second generation of EMS appeared in the early 1970s to the early 21st century and was called the traditional EMS. The founder of this generation of EMS is Dr. Dy-Liacco, who proposed the basic model of power system security control, developed real-time network analysis, optimization, and collaborative control, so in the 1970s, EMS has developed rapidly. my country completed the introduction of the four major power grid dispatching automation systems in 1988, and then completed digestion, absorption, and re-innovation to develop EMS with independent intellectual property rights. At that time, Tsinghua University undertook the introduction, digestion and absorption of the EMS of the Northeast Power Grid. Because the Northeast was a heavy industry base at that time, the network adjustment of the Northeast Power Grid was the largest, and the largest load in the country was in the Northeast. At present, the domestic EMS has been basically localized. The scheduling in this period has already belonged to analytical scheduling and has risen to a new level.

The third generation EMS is a smart grid EMS that is coordinated by the source and network. It appeared after the development of large-scale renewable energy. At this time, there was no multi-energy horizontal cooperation, only the cooperation of the source network. In view of the uncontrollable and volatile characteristics of large-scale renewable energy, a lot of flexible resources are required, from source-transport to charge-distribution. At this time, EMS can integrate and use various distributed resources to develop distributed self-discipline-centralized coordination The architecture, from source, network to Netherlands, has corresponding EMS. There are EMS for wind farms and photovoltaic power plants, EMS for electric vehicles, buildings and homes, and EMS for power transmission, distribution, and micro-grid. These EMS are firstly self-discipline, and then connected together through communication networks to form collaboration. At that time, it can be called the EMS family. There are many members in the EMS family, and different members have different characteristics to jointly realize the source and network collaboration of the smart grid.

The fourth-generation or next-generation EMS is called multi-energy complementary integrated energy management system, that is, IEMS. The integration here is to integrate and integrate various energy sources. Due to the fragmentation of various energy sources and low comprehensive energy efficiency, comprehensive and cascade utilization is required; at the same time, due to the serious lack of flexibility resources, a large amount of wind, water and light, it is necessary to expand to a variety of energy interconnections and find from a variety of energy sources New flexible resources to support the consumption of large-scale renewable energy; through comprehensive optimization and scheduling of maximum benefit, on the premise of ensuring energy supply safety and high quality, reduce energy consumption costs and improve the economic efficiency of comprehensive energy services.

It is like a brain, underneath is a comprehensive energy system, cold, heat, gas, electricity, water, transportation, all kinds of energy flow, called multi-energy flow. At the International Applied Energy Conference (ICAE) held in the UK, the system was recognized as no precedent in the world. The latest result released in 2017 at Tsinghua University, “Multiple Energy Complementary Comprehensive Energy Management System in Park” is the world’s first IEMS product. It is very difficult for the research team to expand the grid EMS for 30 years into IEMS. After 5 years of research and development, and also based on 30 years of grid EMS research and development experience, IEMS was successfully developed.

Main functions of IEMS

Multi-energy flow SCADA. It is used to realize complete and high-performance quasi-steady-state real-time data collection and monitoring functions. It is the basis for subsequent early warning, optimization, and control functions, and uses system software to support the services provided by the platform. Multi-energy flow SCADA is the “sensory system” of IEMS. Based on the Internet of Energy, it collects multi-energy flow data (sampling frequency: electricity is in the second level, and heat/cooling/air is in the second or minute level) to complete the corresponding monitoring function. And provide the data to the state estimation and subsequent advanced application function modules, receive the system operation control instructions, and send them to the system equipment for execution through remote control/remote adjustment signals. The multi-energy flow SCADA function interface includes energy flow distribution, field station wiring, system functions, comprehensive monitoring, operation information, analysis and evaluation, and intelligent alarm.

Multi-energy flow state estimation. Due to the wide distribution of measurement points in the multi-energy flow sensor network, the variety of measurement types, the low data quality, the difficulty of maintenance, and the high cost sensitivity, it is inevitable that incomplete data collection and errors will occur. Therefore, the multi-energy flow network needs state estimation technology to provide real-time, reliable, consistent and complete network state, which provides a basis for the evaluation and decision-making of IEMS. Multi-energy flow state estimation can complete the measurement data and eliminate the bad data, so that the bad data can be estimated, detectable, and identifiable, and ultimately reduce the number of sensor installations, reduce the complexity of the communication network, and reduce the investment and cost of the sensor network. The effect of maintenance costs improves the reliability of assessment and decision-making by improving the reliability of basic data, and reduces the risk of energy network operation accidents.

Multi-energy flow safety assessment and control. The importance of safety is self-evident, and the safety of the energy system is particularly related to the safety of life and property. On the one hand, it is necessary to establish the concept of the “N-1″ safety criterion. This concept is to pay attention to the weakest link and make a plan. An example was given at the press conference of our achievements this morning. It was said that a recent major power outage in Taiwan was caused by the failure of a gas valve. Then that valve is a weak link in the gas-electricity coupling energy system. Therefore, we must always pay attention to the weak links, and there must be a plan for problems, otherwise we will face huge risks. On the other hand, it is necessary to pay attention to the security control of the transaction gate of the park. The capacity allocation and operation cost of the park gate is a key issue. On the one hand, the larger the capacity, the higher the investment cost of the transformer, and on the other hand, the larger the capacity, the capacity fee charged by the grid company The higher. For example, the total cost of investment and operation of 50 MW capacity and 100 MW capacity is very different. If it is designed as a 50 MW capacity, the transformer will be burned in case the actual capacity is exceeded. How to control the gate flow within 50 megawatts is the problem of safety control. In a multi-energy flow system, different energy systems are coupled and influenced by each other. A certain part of the faults and disturbances will affect other parts of the multi-energy flow system, which may cause a chain reaction, so coupling analysis is required. You can use the flexibility provided by the inertia of heat, gas and other systems to provide new means for the safety control of electrical systems. You can use these new means to do collaborative safety control.

Multi-energy flow optimization scheduling. There are several important concepts here: start-stop planning, day-to-day scheduling, day-to-day scheduling, and real-time control. A park or a city’s triple supply, gas unit, and electric boiler can be started and stopped. Some equipment can be stopped to reduce costs. This can be started and stopped according to the optimal start and stop plan determined a few days ago. Then adjust how much output is based on the start and stop, this is the day-to-day scheduling. Intra-day dispatching is due to changes in wind power output and load changes, so it is necessary to reschedule within the day to adapt to the new suitable power generation output and maintain the optimal balance between output and load. Finally, when the second level is reached, control is required. For network security, voltage regulation, and frequency modulation, real-time control is required. The time scale for scheduling is longer, generally in units of 15 minutes, and the control is in seconds, and the time scale is shorter. In a multi-energy flow system, there are more controllable methods than a single energy system. From the perspective of source grid load storage, comprehensive scheduling and control of cooling, heating, gas, and electricity can be achieved.

Energy price of multiple energy flow nodes. A park or smart city must consider building a very good internal business model. The internal business model is not external, not on top, but on the users in the park. What should such a business model look like? The most scientific model is the node price model. The node energy price model first needs to be calculated to determine the energy consumption cost in various places. The energy consumption cost includes four parts: one is the cost of energy emission; the second is the cost of transmission loss; the third is the cost of network congestion; four It is the cost of multi-energy coupling. Then it is necessary to scientifically and accurately calculate the energy price of each node, including the price of cold, heat, gas and electricity, and the price of different times and different locations. Only through accurate calculation can the total energy cost of the park be significantly reduced, because You can use price signals to guide users to use energy. In this way, the energy cost of the entire park can be significantly reduced by flexible energy prices.

The node energy price is set according to the supplier’s marginal cost of production. When the line is blocked, the price of each node presents different prices according to the location. The real-time price can stimulate the flexibility of the user side. The node energy price reflects the cost scientifically, which is conducive to establishing a fair internal market mechanism.

Multi-energy flow virtual power plant. The virtual power plant is a business model for the upper market. The entire park or city can be turned into a large virtual power plant. Although it is not a physical power plant, there are many distributed power sources such as energy storage and combined heating, cooling, and power. Into a large adjustable market player. Because of the small capacity and large number of distributed resources, it is difficult to manage the market individually. Through the collection of virtual power plants, multiple distributed resources can be coordinated and optimized through software architecture to provide peak shaving, frequency modulation, voltage regulation and other services for external markets. Conducive to the optimal allocation and utilization of overall resources. Such a business model can bring high economic benefits, which has become a reality in the United States.

Based on optimized dispatching, the virtual power plant can aggregate the distributed power supply, controllable load and energy storage devices in the park into a virtual controllable set, so that the park can participate in the operation and dispatch of the upper-level power grid as a whole. The virtual power plant coordinates the contradiction between the higher-level power grid and distributed resources, fully exploits the value and benefits that distributed resources bring to the power grid and users, and realizes friendly interaction with the power grid.

The following figure shows the internal composition architecture of a multi-energy flow virtual power plant

Laterally, it is the source net load storage. The source side includes conventional power supply equipment, CHP units, gas boilers and other equipment, as well as external grid power supply and renewable energy access; the grid is divided into cold and heat and other transmission systems; the Dutch side is the electricity, heat and cold load inside the park In terms of energy storage, different energy subsystems have their own energy storage equipment. In the longitudinal direction, electricity, gas, heat, and cold multi-energy complement each other. Different energy subsystems are represented with different colors, and multiple energy conversion equipment (heat pumps, CHP, gas boilers, lithium bromide units) couple different energy subsystems. Various energy forms in the park are combined and operated in the form of virtual power plants. On the premise of ensuring reliable supply of electricity, heat and cooling loads, cascade utilization of energy is realized, energy efficiency is improved, and energy cost is reduced. And for the highly volatile renewable energy, the integrated energy system has more flexibility, which promotes the acceptance of renewable energy and further improves the economics of the system.

IEMS application case

The “Internet+” Smart Energy (Energy Internet) Demonstration Project in Chengdu Hi-tech West District. Chengdu West High-tech Zone is an industrial park of about 40 square kilometers. The IEMS system analyzes the supply and demand of comprehensive energy here to achieve multi-energy collaborative optimization. Focusing on the demand for energy such as electricity, gas, cooling, and heat, the construction of an energy internet demonstration park based on a clean energy hub (natural gas cold and heat combined supply, photovoltaics, wind power, etc.) will be carried out to achieve natural gas and geothermal energy in the high-tech west zone , Wind and solar energy, steam, cold water, hot water, electricity and other energy management.

Guangzhou Conghua Industrial Park’s comprehensive energy management system R&D and demonstration project. The core part of this park is about 12 square kilometers and it is also a typical industrial park. The energy pattern of the industrial park is characterized by large capacity, multi-energy flow, and high penetration. It has good basic conditions for multi-energy collaboration and multi-energy optimal dispatching. It is more suitable for the demonstration of the “Internet+” smart energy integrated energy service business model. Area. Build an IEMS system in the park, propose a virtual power plant and user demand-side response mode, implement flexible resource cluster synchronization control technology, and finally the system realizes deployment applications.

R&D project of smart energy energy operation control system in Lisha Island, Dongguan, Guangdong. Dongguan Lisha Island is also an industrial park of about 12 square kilometers. The Lisha Island smart energy system is divided into the following four levels: first, the energy regulation of the park under the coupling of thermoelectricity; second, there are constraints when the policy is not liberalized Conditional energy management of the park; third, regional energy management with the policy fully liberalized; fourth, interaction (transaction) between the future and the large system to create an integrated energy supplier. The research and development of the energy management system is divided into four stages: first, the overall is considerable and partially controllable; second, the overall is controllable and partially optimized; third, the overall optimization and part of the interaction; fourth, the overall interaction and joint optimization.

Jilin Province multi-energy flow comprehensive energy management and optimization control research project. The proportion of thermal power units in Jilin Province is large, and there is no flexible storage power supply such as pumping and gas. Jilin is located in a cold area. The heating period in winter is up to half a year. More than 90% of the thermal power units are heating units. During heating, the minimum output of thermal power exceeds The province’s minimum load, large wind power absorption pressure, and the problem of wind abandonment are very serious. The main reason is that the heat-electricity control relationship of the heating unit and the “fixing electricity with heat” mode significantly reduce its peak shaving capacity and occupy the wind power space. How to use the market means to stimulate the control and trading of multi-energy flow is the most challenging problem. For this reason, the IEMS system was deployed to study the market trading mechanism of multi-energy flow integrated system, study the cost-effectiveness of multiple market players, and study In addition, the energy-consuming alternative response in the demonstration area is designed, and the multi-energy flow integrated energy management optimization control technology is proposed to solve the problem of large-scale wind power consumption while achieving clean heating.

In the process of the energy internet from “concept” to “landing”, there are still many new ideas, new technologies, new applications, which will be sorted out and shared with you in the future, hoping to help everyone’s work and study.