Electronic Enthusiasts Network reported (text / Cheng Wenzhi) Over the years, the power generation resources in the power system have shown a trend of clean and decentralized development. The grid-connected operation of these new power generation resources not only promotes energy conservation and emission reduction, but also provides Distribution network, transmission network, power quality, system protection and dispatch operation bring a series of challenges. In addition, these distributed generation resources are small in scale and scattered in layout, which makes it difficult for them to truly participate in the economic dispatch of the power system and even the competition in the power market, and it is difficult to discover their economic value through the market. In order to meet the challenges and give full play to the positive role of new energy sources, "Virtual Power Plant (VPP)" has attracted people's attention.

What is a virtual power plant? What are its characteristics?

In fact, as early as 1997, the concept of virtual power plant appeared in Dr. Shimon Awerbuch's book "Virtual Public Facilities: Description, Technology and Competitiveness of Emerging Industries". Around 2007, there was a systematic discussion of virtual power plants in the world, and after 2012, related research reports gradually increased.

At present, although there is no unified definition of virtual power plant, it is generally believed that virtual power plant is a combination of Distributed Generation (DG), Dispatchable Load (DL) and Distributed Energy Storage (DES). ) organically combined to realize the carrier of integrated regulation of various distributed energy resources through supporting regulation technology and communication technology. Its core is a centralized control platform for regulating the energy flow of DG, DL, and DES. That is to say, it is a smart grid technology that integrates distributed generation, demand-side response, and energy storage resources in a unified and coordinated manner, and responds to grid dispatch instructions. The virtual power plant is expected to manage distributed energy through the information communication technology and software system in the centralized control platform, and to aggregate, coordinate and optimize the control of relatively scattered power sources, power grids, loads and energy storage. Among them, the centralized control platform has a large number of core capabilities: "generating end-load end": aggregation coordination and optimization control. The centralized control platform for virtual power plants is built mainly by local power companies, which can analyze the collected data such as charging piles and residential electricity consumption, and achieve accurate response and management at the load end. When the power supply at the load end is insufficient, it can be used as a "positive power plant" to supply power to the power system; when the power generation end is too large and the load end is difficult to carry, it can be used as a "negative power plant" to increase the load to absorb the power of the power system and help the power The market slashing peaks and filling valleys can smooth a series of impacts brought by the grid connection of new energy to the power grid. Electricity market: Multi-terminal entities realize interoperability and optimize power regulation capabilities. The virtual power plant can interconnect the large power grid and the power trading market, which not only helps to optimize the entire power grid system, but also provides internal aggregation of enterprises, users, charging piles, energy storage, distributed energy and other market entities to participate in the power marketization. The way of trading allows them to become micro-generators and participate in electricity market transactions to obtain arbitrage income. At the same time, when the price signal is known, the virtual power plant can first calculate the maximum adjustment ability, and then calculate the price report of the unit adjustment amount, so as to give full play to the adjustment ability of various resources.

Characteristics and Core Technology of Virtual Power Plant

Compared with traditional power plants, virtual power plants have more advantages. On the premise of ensuring the safe and stable operation of the system, virtual power plants can achieve the goals of obtaining economic benefits from renewable energy, reducing power generation costs, reducing greenhouse gas emissions, and optimizing resource utilization. Specifically, the virtual power plant has the following characteristics: First, the resources in the virtual power plant are diverse. It can aggregate and manage a variety of renewable energy generating units, such as photovoltaic generating units, wind generating units, small hydroelectric generating units, micro cogeneration units, etc. Each resource has its own output characteristics and needs to be coordinated and operated. The virtual power plant can also adjust the controllable load according to the time-of-use electricity price, and use the energy storage device to charge and discharge, thereby changing the output of the virtual power plant and presenting virtual power generation characteristics to the power grid. Secondly, the assets of virtual power plants are virtual. The assets inside the virtual power plant are not necessarily owned by the virtual power plant agent. The relationship between the virtual power plant agent and the asset is mainly the dispatch of energy flow, the allocation of currency flow and the sharing of information flow, which is similar to the dispatch of traditional power grids, and the relationship between transaction centers and assets. relationship between power plants. Third, the operation of virtual power plants requires synergy. Virtual power plants aggregate a variety of renewable energy sources with different output characteristics, different power generation costs, and different suppliers. Therefore, in order to realize the effective production of virtual power plants in the electricity market, it is necessary for multiple virtual power plants to communicate with each other in different operating agencies. Cooperate and cooperate. From the perspective of technology trends, the current construction of virtual power plants focuses on four core technologies: 1) Intelligent metering: It can accurately measure the consumption of electricity, heat, gas, and water on the user side, quickly capture data changes, and more proactively report to the system Early warning of equipment failure. 2) Information communication: two-way communication technology, which can not only receive the current status information of each unit, but also send control signals to the control target. 3) Coordinated control: Utilize optimization algorithms and communication control technology to help virtual power plants store and process massive power data, analyze and predict power loads and regulated and regulated loads, and efficiently complete response distribution. 4) Information security protection: There are interfaces between the virtual power plant and the industrial control system of each distributed energy station, the user-oriented power consumption information system, the public marketing information system, and the power grid dispatching information system, so as to ensure system security protection.

Application example of virtual power plant

At present, there are already some application cases of virtual power plants in Europe and the United States for reference. Since 2001, Europe has started a virtual power plant research project with small distributed power generation units as the main target, and participating countries include Germany, the United Kingdom, Spain, France and Denmark. From 2005 to 2009, 20 research institutions and organizations from 8 EU countries cooperated to implement and carry out the FENIX project, hoping to maximize distributed energy resources by aggregating distributed energy resources into large virtual power plants and decentralized management. The contribution of the power system, get rid of the traditional management of small units of the power system. In 2012, the European virtual power plant was officially launched. Statkraft, a Nordic energy company, established the first virtual power plant in Germany. The power generation capacity is equivalent to 10 nuclear reactors. Today, European virtual power plants have begun to be commercialized, and the business model is mainly based on the aggregation of power resources. For example, Next Kraftwerke, founded in 2009, is the largest virtual power plant manufacturer in Germany and even in Europe. It has obtained the European Electricity Exchange Market (EPEX) certification, and can participate in energy spot market transactions on European exchanges such as EPEX SPOT and EEX, and transmit electricity in seven European markets. The Transmission System Operator (TSO) provides balancing services in the TSO region. The services it provides for the electricity market mainly include: 1) System construction: Provide software services through the network: In addition to running virtual power plants, NEXT also provides customizable virtual power plants (NEMOCS ) services, providing software solutions for energy companies to build their own virtual power plants. In addition, NEXT also provides the power system balance area management software (NEXTRA). 2) Power consumption: Adjusting power resources according to daytime market signals, NEXT Company adjusts the output and demand of dispatchable energy generating units (such as biogas plants) and loads in its resource pool according to power market fluctuations, bringing income to these customers , while contributing to the balance of the system. 3) Balancing Services (Power Trading): Balancing services using aggregated energy resources: NEXT companies are active in all three balancing markets. As of mid-2021, NEXT has accumulated 2,780MW of virtual power plant resources to provide balancing services (75MW primary reserve, 983MW secondary backup, 1762MW tertiary backup). Its clients earn revenue by participating in the balanced market. NEXT companies get a cut of the revenue. The United States seldom adopts the concept of virtual power plants, but mainly promotes demand response using controllable loads on the user side, and has achieved many results. Virtual power plant projects in the United States mainly focus on demand-side management, combined with the relevant mechanism of demand response, and take into account the utilization of source-side renewable energy. Therefore, load control and energy storage equipment investment account for the main part of their virtual power plants. From a geographical point of view, the virtual power plant market in the United States is represented by three regions: California, Vermont and New York: California is the earliest state in the United States to carry out power demand side management, while Vermont is the first to propose the concept of virtual power plants and put them into practice. Implementing state. In terms of specific applications: In 2017, Green Mountain Power in Demont, USA built its own virtual power plant platform to connect to more than 2,000 home customers. In 2022, Pacific Gas & Electric (PG&E) and Tesla are launching a new pilot program to help stabilize the grid by creating virtual power plants. Currently, Tesla has invited about 25,000 PG&E customers with Powerwalls to join the virtual power plant. In terms of business models, virtual power plants in the United States are usually operated by public utility companies, mainly using equipment rental models. Take the Con Edison project, for example: Sunverage provides lithium-ion battery storage systems, SunPower leases its solar panels, and utility Con Edison manages grid power for stored electricity, primarily for self-contained single-family homes. In addition, the virtual power plant in Vermont mainly adopts the system benefit charging model. my country also proposed the concept of virtual power plants around 2000. It started from the Northeast spot market. Later, in order to balance the account deficit, a market-oriented reform was proposed in 2007. However, the domestic spot cannot reach the scale of foreign countries. It is impossible to place 80% of the electricity in the spot market like foreign markets. Our country will not simply learn from Europe or the United States, but will adopt a hybrid type, which has both power and load types. For example, the most advanced virtual power plant in my country represents the Jibei Electric Power Virtual Power Plant Demonstration Project is a hybrid type. It was officially launched in December 2019. After being put into operation, it will access 11 types of flexible resources in real time, with a capacity of about 226 MW, covering the three cities of Zhangjiakou, Qinhuangdao and Langfang. ABB Group leveraged its rich experience in implementing virtual power plants in Europe and its leading technology in the field of control to provide 9 types of users from different industries in the Jibei Electric Power Virtual Power Plant project, such as distributed photovoltaics, air source heat pumps, residential and industrial air conditioning units , electric vehicle charging stations and other users have customized corresponding intelligent distribution metering and coordinated control solutions. Since the "14th Five-Year Plan", many provinces and cities across the country, including Beijing, Shanghai, Shenzhen, Jiangsu, and Hebei, have begun pilot construction of virtual power plants and have officially put them into operation. On May 20, 2022, the virtual power plant platform deployed in SDIC Shenzhen Energy Development Co., Ltd. issued an instruction to dispatch Shangcheng New Energy Clamdi intelligent charging station to transfer 50 kWh of electricity from 0 to 4 o'clock. According to the data of Guangdong electric power spot market on May 26, Shenzhen Energy made a profit through this test, with an average income of 0.274 yuan per kilowatt-hour.

Epilogue

Generally speaking, the research in the field of virtual power plants in my country is still in its infancy. In order to adapt to my country's specific national conditions such as geography, weather, power generation type structure, etc., the structural form and functional configuration of virtual power plants in my country must be designed and adjusted in a targeted manner. However, judging from the urgent need for economic and environmental protection of power energy in my country and the rapid development trend of the scale of new energy power generation, virtual power plants will have a broad space for development in my country. Of course, China is still in its infancy. The installed capacity is in the 100 MW scale, and the GW level has not yet appeared. Under the promotion of domestic policies, the virtual power plant industry should usher in a period of rapid development in the next 3 or 4 years. By 2030, the market size will reach 100 billion yuan.

Reviewing Editor: Peng Jing

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