Virtual Power Plant - Through Advanced Information Communication Technology and Software System

A virtual power plant is a kind of coordination and optimization of DERs, such as DG, energy storage systems, controllable loads, and electric vehicles, through advanced information and communication technology and software systems, so as to participate in power supply coordination and management of power markets and grid operations as a special power plant system. The core of the virtual power plant concept can be summarized as "communication" and "aggregation". The key technologies of virtual power plants mainly include coordinated control technology, smart metering technology and information communication technology. The most attractive function of the virtual power plant is that it can aggregate DER to participate in the operation of the electricity market and ancillary service market, and provide management and ancillary services for the distribution network and transmission network. The solution idea of "virtual power plant" has a very large market potential in our country, and it is undoubtedly a good choice for China facing "the contradiction between power shortage and low energy efficiency".

In September 2018, the "Virtual Power Plant" standard was approved by the International Electrotechnical Commission (IEC), becoming the first batch of international standards in this field in the world.

1. The development history of virtual power plant

As the world's energy shortage, environmental pollution and other issues become increasingly prominent, distributed generators (DG) are adopted by more and more countries because of their reliability, economy, flexibility and environmental protection. However, despite the outstanding advantages of DG, there are still many problems. First, the small capacity, large quantity, and uneven distribution of DGs make the cost of single-machine access high, often invisible to system operators and even difficult to manage; secondly, the access of DGs has brought many technical difficulties to the stable operation of the power grid, such as Power flow changes, line congestion, voltage flicker, harmonic effects, etc.; again, the current "fit and forget" DG operation mode and the limitation of power market capacity have further hindered the large-scale grid connection of DG.

Today, the power industry around the world is rapidly transforming, and the power system should operate based on the market. However, due to the characteristics of DGs, such as small capacity or their intermittent and random nature, it is not feasible to join the power market operation by themselves. However, aggregating DG into an integrated entity provides a solution to this problem.

Most of China adopts the concept of micro-grid as the grid-connected form of DG. It can well coordinate the technical contradiction between large power grid and DG, and has certain energy management functions. However, the main control target of micro-grid is DG and the local application of users. , and limited by geographical regions, there are certain limitations to the effective utilization of multi-regional and large-scale DG and the scale benefits in the power market. Active distribution network is another effective solution to achieve large-scale DG grid-connected operation. Its concept expands the access radius of DG to a certain extent, and can implement active management of distribution network, but it can present DG to Insufficient consideration is given to the benefits of large power grids and power markets. The proposal of virtual power plant (VPP) provides a new idea to solve these problems.

The term "virtual power plant" originated from the definition of virtual public facilities in Dr. Shimon Awerbuch's book "Virtual Public Facilities: Description, Technology and Competitiveness of Emerging Industries" in 1997: virtual public facilities are independent and market-based It is a flexible cooperation among entities driven by energy, which can provide consumers with the high-efficiency electric energy services they need without owning corresponding assets. Just as virtual public facilities use emerging technologies to provide consumer-oriented electric energy services, virtual power plants have not changed the way each DG is connected to the grid, but aggregate DG, energy storage systems, and Different types of distributed energy resources (distributed energy resource, DER) such as load control and electric vehicles, and realize the coordinated and optimized operation of multiple DERs through a higher-level software architecture, which is more conducive to the rational and optimal allocation and utilization of resources. The concept of a virtual power plant puts more emphasis on the functions and effects presented to the outside world, updating the operating concept and generating social and economic benefits. Its basic application scenario is the electricity market. This method can aggregate DERs to stably transmit power to the public grid without the need for transformation of the power grid, and provide fast-response auxiliary services, becoming an effective way for DERs to join the power market, reducing the risk of imbalance in their lonely operation in the market, and gaining scale Economic benefits. At the same time, the visualization of DER and the coordinated control optimization of virtual power plants have greatly reduced the impact of DER grid-connected on the public network in the past, reduced the difficulty of dispatching caused by DG growth, made power distribution management more reasonable and orderly, and improved The stability of system operation.

In September 2018, the installed capacity of wind power and solar power in China increased by an average of 44% and 191% annually, much higher than the global average growth rate. However, wind energy, solar energy and other random, intermittent, and fluctuating characteristics, large-scale, high-proportion access will bring a series of challenges to the balance of the power system and the safe operation of the grid.

In February 2022, the construction of the first batch of 15 virtual power plants declared by 9 electricity sales entities in Shanxi was completed, with a copolymerization capacity of 1,847,400 kilowatts and an adjustable capacity of 392,000 kilowatts.

2. International Standards for Virtual Power Plants

In October 2017, an expert team composed of State Grid Jibei Electric Power Company and China Electric Power Research Institute submitted a proposal to the International Electrotechnical Commission (IEC) on behalf of China. After fierce competition, it was officially approved this year and became the first batch of IEC international standards in the field of virtual power plants.

On September 21, 2018, it was learned from the State Grid Corporation of China that the two "virtual power plant" standards initiated by it were approved by the International Electrotechnical Commission (IEC), and became the first batch of international standards in this field in the world, filling the gap in the industry.

3. Definition of virtual power plant

From the perspective of the whole world, the research and implementation of virtual power plants are mainly concentrated in Europe and North America. According to data released by Pike Research, as of the end of 2009, the total capacity of global virtual power plants was 19.4 GW, of which Europe accounted for 5,100 and the United States accounted for 4,400; by the end of 2011, the total capacity of global virtual power plants had increased to 55.6 GW. However, the application forms of virtual power plants in Europe and the United States are significantly different, and virtual power plants in European countries also have their own characteristics. The virtual power plant projects that have been implemented in Europe, such as the EU virtual fuel cell power plant (VFCPP) project, the Dutch virtual power plant project based on power matcher, the EU FENIX (flexible electricity network to integrate expected) project and the German professional The virtual power plant (professional VPP, ProViPP) pilot project is mainly aimed at achieving the goal of reliable grid connection and power market operation of DG. DG occupies the main component of DER; while the virtual power plant in the United States is mainly developed based on the demand response plan, taking into account Considering the use of renewable energy, the controllable load occupies the main component. Therefore, although the concept of virtual power plant has been put forward for more than ten years, there is no unified definition of the framework of virtual power plant.

In the literature, a virtual power plant is defined as an energy Internet that relies on software systems to remotely, automatically allocate and optimize power generation, demand response, and energy storage resources; in the literature, a virtual power plant is defined as the same network as an autonomous microgrid ; In the literature, a virtual power plant is defined as a combination of many cogeneration generators connected to the low-voltage distribution network; collection; in the literature, a virtual power plant is defined as a multi-technology and multi-site heterogeneous entity; in the literature, a virtual power plant is composed of a series of technologies with rich operation modes and availability that can be connected to any node of the distribution network; in In the literature, a virtual power plant is defined as an information communication system that aggregates controllable distributed energy (CDE) units or active customer network (ACN) in a direct centralized control manner.

On the whole, the core of the virtual power plant concept can be summarized as "communication" and "aggregation". The virtual power plant can be considered as the aggregation and coordination optimization of DG, energy storage system, controllable load, electric vehicle and other DERs through advanced information communication technology and software system, so as to participate in the coordinated management of power supply in the power market and grid operation as a special power plant system.

4. Prospects for virtual power plants

The idea of "virtual power plant" to solve the power crisis is also reflected in its great adaptability to the power supply and demand situation. As the world's second largest power generation country after the United States, my country's power supply scale has reached a considerable level. Therefore, it is obviously inappropriate to attribute the "power shortage" problem that plagues us to the scale of power generation. High energy consumption has always been a serious problem in my country's economic life. According to relevant statistics, China's electricity consumption per unit of GDP is 3.8 times that of the world average, 3.1 times that of South Korea, and 11 times that of Japan. Low energy utilization efficiency and serious waste of resources are undoubtedly one of the crux of the power shortage. The other side of high energy consumption is the great potential for energy saving. China has a lot of high-energy-consuming equipment, and lighting equipment, boilers, refrigeration and air conditioning, etc. all need to be improved in efficiency. According to estimates, the total power-saving potential of China's end-use equipment is about 200 billion kWh. The National Development and Reform Commission's energy-saving plan requires that by 2020, China's energy consumption per 10,000 yuan of GDP will drop from 2.68 tons of standard coal in 2002 to 1.54 tons of standard coal, forming an energy-saving capacity of 1.4 billion tons of standard coal, a large part of which It needs to be done by power saving.

The solution idea of "virtual power plant" has a very large market potential in our country, and it is undoubtedly a good choice for China facing "the contradiction between power shortage and low energy efficiency".

5. Key technologies of virtual power plants

5.1 Coordinated Control Technology

The control objects of the virtual power plant mainly include various DGs, energy storage systems, controllable loads and electric vehicles. Since the concept of a virtual power plant emphasizes the functions and effects presented to the outside world, it is the focus and difficulty of the coordinated control of virtual power plants to aggregate and diversify DERs to achieve high-demand power output for the system. In fact, some renewable energy power stations (such as wind power stations and photovoltaic power stations) have the characteristics of intermittent or randomness and prediction errors. Therefore, the influence of uncertainty must be considered in large-scale grid connection. This requires the reasonable cooperation of energy storage system, distributable generator set, and controllable load to ensure power quality and improve power generation economy.

5.2 Smart Metering Technology

Smart metering technology is an important part of the virtual power plant and an important basis for realizing the monitoring and control of DG and controllable loads in the virtual power plant. The most basic function of the smart metering system is to automatically measure and read the consumption or production of electricity, gas, heat, and water in the user's residence, that is, automated meter reading (AMR), so as to provide power for the virtual power plant and real-time information on the demand side. As the development of AMR, automatic meter management (AMM) and advanced metering infrastructure (AMI) can remotely measure real-time user information, manage data reasonably, and send it to relevant parties. For the user, all metering data can be displayed on the computer through the user's home area network (HAN). Therefore, users can intuitively see information such as the electric energy they consume or produce and the corresponding costs, so as to take reasonable adjustment measures.

5.3 Information and communication technology

The virtual power plant adopts 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. The communication technologies used in virtual power plants mainly include Internet-based technologies, such as Internet protocol-based services, virtual private networks, power line carrier technologies, and wireless technologies (such as Global System for Mobile Communications/Universal Packet Radio Service (USM/UPRS) wait). In the user's residence, communication technologies such as WiFi, Bluetooth, and ZigBee constitute an indoor communication network.

6. Operation of the virtual power plant

The most attractive function of the virtual power plant is that it can aggregate DER to participate in the operation of the electricity market and ancillary service market, and provide management and ancillary services for the distribution network and transmission network.

7. Commercial type of virtual power plant

Commercial virtual power plant is a virtual power plant considered from the perspective of commercial benefits, and it is a flexible expression of DER investment portfolio. Its basic function is to formulate the optimal power generation plan and participate in market bidding based on user demand, load forecast and power generation potential forecast. Commercial virtual power plants do not consider the impact of virtual power plants on the distribution network, and add DERs to the electricity market in the same way as traditional power plants.

Each DER in the commercial virtual power plant portfolio submits information such as operating parameters and marginal costs to it. These inputs are combined to create a unique profile that represents the combined capacity of all DERs in the portfolio. Combined with market intelligence, the commercial virtual power plant will optimize the potential return of the investment portfolio, develop a generation plan, and participate in the market bidding with traditional power plants. Once the bidding has obtained market authorization, the commercial virtual power plant will sign a contract with the power trading center and the forward market, and submit the DER generation schedule and operating cost information to the technical virtual power plant.