First, the rapid development of distributed photovoltaics has become the main force of distributed energy
“Distributed” energy is compared to the traditional “centralized” energy utilization method. It refers to an energy comprehensive utilization system that is established near the user's load center instead of long-distance transmission, covering power generation, cogeneration, and storage. Energy and energy management systems and other forms, such as home solar power systems or household wall-mounted gas heating systems, are common distributed energy sources. Early distributed energy sources were developed on the basis of CHP (Chemical Heat and Power Cogeneration System). Later, the distributed energy system gradually expanded to users' multiple types of cold, heat, electricity, and steam (CCHP). System and renewable energy power generation system.
As China continues to push forward structural reforms on the energy supply side, and promotes changes in energy development methods from extensive to quality-enhancing and efficiency-enhancing, distributed energy sources such as photovoltaics, natural gas, wind power, biomass, and geothermal energy have become China's response to climate change. The important content of safeguarding energy security.
Natural gas distributed energy developed earlier. According to the forward-looking data of the “China's Distributed Energy Industry Business Model Innovation and Investment Prospects Forecast Report from 2018 to 2023”, the cumulative natural gas distributed generation capacity in China was 12 million kilowatts in 2016, which is less than 2% of the national total installed capacity. From the “Guidance on the Development of Distributed Natural Gas”, there is a big gap between the target of 50 million kilowatts installed by 2020.
In recent years, China's distributed photovoltaics have seen explosive growth. The “China Clean Energy Industry Annual Development Report” shows that in 2017, China's installed photovoltaic power generation capacity continued to grow rapidly, with 53.06 GW of new installed capacity, ranking first in the world for five consecutive years, an increase of 53.6% year-on-year. Among them, distributed photovoltaics added 19.44 GW, an increase of 3.7 times year-on-year. As of the end of 2017, the cumulative installed capacity of photovoltaic power generation in China reached 130 GW, of which, photovoltaic power stations were 100.59 GW and distributed photovoltaics were 29.66 GW.
Compared with distributed photovoltaics, decentralized wind power development is relatively slow. Experts in the industry have stated that many institutional and institutional issues have resulted in few scattered wind power, but the reference to developed countries is basically distributed. Only with the combination of the user side and the demand side, there is hope for the future. If decentralized wind power does not work, China’s wind power may not be promising. In 2018, in addition to wind power will continue to develop into the load center, China's southern Middle East, decentralized wind power will become the "next field."
In addition, distributed energy sources such as distributed geothermal, biomass, and multi-energy complementary projects are also moving forward.
Second, high-efficiency distributed energy is more conducive to new energy consumption
"Promoting the revolution in energy production and consumption and constructing a clean, low-carbon, safe, and efficient energy system" is an important clarification of China's energy system construction in the Nineteenth Congress. Developing distributed is a reasonable choice for energy transformation. Zhang Yuqing, former deputy director of the National Energy Administration, pointed out that distributed energy has the advantage of high energy efficiency, and is an important trend for China's future energy development. It is necessary to actively promote distributed energy as an important energy source. Energy efficiency distributed energy systems, much higher than most countries rely on large-scale power plant will mainly concentrate supply system from the power plant to the end user a one-way transmission. Theoretically speaking, "large units, large power grids, and UHVs" are highly efficient, but this is only in the energy conversion and transmission sectors. If the analysis from the entire energy system, the conclusion is not the case. Although the large thermal power generation unit has high power generation efficiency, due to the limitation of the heating scale and the heating radius, the waste heat from the power generation cannot be used, so the energy utilization efficiency cannot be compared with the distributed energy. Power plants eventually can only convert 1/3 of the thermal energy generated by the combustion of fuel and energy into electricity, and nearly 50% of the thermal energy is lost. The transmission links lose nearly 10% of the thermal energy. Because distributed energy can be used to generate heat and cool the waste heat of the medium after power generation, energy can be used in a reasonable step. Users can transmit power to the grid and purchase power according to their own needs. The efficiency of energy utilization reaches more than 80%, and some designs are well-designed. Distributed energy can reach 90% or even higher.
As industry experts say, whether energy is distributed or concentrated is closely related to changes in energy structure, energy technologies, and energy demand. In the past, China’s energy structure was dominated by coal, which determined that its facilities were becoming larger and larger and the energy system more and more centralized. But now, China's natural gas and renewable energy sources are accelerating, and clean energy such as wind power and solar energy is itself dispersed. It is necessary to study how these energy sources can be directly used in their place of occurrence.
Distributed energy is an important way to solve the problem of new energy use. Although the total installed capacity of wind power and solar energy in China has reached the first place in the world, the phenomenon of “discarding the wind” and “abandoning the light” is still serious. Large new energy bases are mainly concentrated in the western and northwestern regions. However, the local electricity market has limited capacity. To make full use of electrical energy, it is necessary to use the UHV power transmission system to transport electricity over long distances to economically developed eastern regions. However, the cost of transportation in this way is too high. In addition, the natural volatility of new energy sources will also impact the grid system. If we want to break through this bottleneck, the adoption of distributed energy is a viable path, and it is also a clear idea for the development of the Chinese government. The greatest advantage of this approach is that the power generation facilities are relatively close to the load center, and can avoid the problem of “discarding winds” and “discarding light” to some extent. According to industry sources, the essence of renewable energy is distributed.
Distributed energy sources can be the peak load of the power system, improving the reliability of power supply, and it is also a very economical option for power supply in remote areas. The natural gas distributed energy project requires only a small amount of investment to increase peak heating equipment for cooling and heating (for example, gas-fired generators and direct-fired-gas turbines for the joint triple supply project, as long as additional burners are added to the direct-fired turbine; for example, the gas-fired thermoelectric project only Gas-fired boilers that need to be equipped with peaking, etc.) can be used as an interruptible and adjustable power generation system, which can provide cold, heat and electricity for the surrounding area and can also be used for peak regulation of the power grid. As a regional energy supply system, the distributed energy system is mainly built on the power distribution side. It has the characteristics of adapting to local conditions, supporting facilities nearby, drawing materials nearby, and using it immediately. Whether the blackouts in the northeastern United States and eastern Canada in 2003 or the blackouts in Shenzhen in 2012 all indicate that there is a shortage of emergency power sources – there are many hidden dangers in the construction of distributed energy. Even if there is no accident, the burden of the municipal power grid will be too large every year during the peak period, and the construction of a distributed energy system will have the advantage of peaking and filling valleys and alleviating power shortages. After an extreme disaster or a traditional transmission and distribution system accident, distributed energy sources can ensure the supply of local basic energy to a certain extent, effectively increase the reliability of energy supply, and increase the safety of the entire energy system. As many remote and rural areas of China are far away from the large power grids, these areas cannot or will not enjoy the benefits of the expansion of large-scale power grid construction, because the cost of long-distance power supply investment maintenance is too large, or because some areas do not have natural conditions to build The conditions of the power supply network are centralized, and distributed generation is a good solution to these problems and brings a new solution to the power supply in underdeveloped regions.
Third, the development of distributed energy expects policy support
At present, the development of distributed energy also faces many challenges. According to industry insiders, due to unclear policies and difficult policies, distributed energy projects have encountered challenges in spare capacity, power access methods, government fund reductions, and natural gas price discounts. In addition, distributed energy projects are generally new construction projects, and the initial production rate is often less than 50%, but usually the company can only make profits when it reaches 60% to 70% load utilization. How to achieve distributed energy projects? The economical nature of the incubation period remains to be explored.
Wu Gang, chairman of Xinjiang Goldwind Science and Technology Co., Ltd., stated that at the “crossroads” of wind power industry development, decentralized wind power is considered to be the next blue ocean. However, for distributed PV, the approval procedures for decentralized wind power projects are more complicated. Currently implemented distributed energy projects are mostly in the form of two or more energy combinations. When the developer applies for approval, a distributed energy project needs to be disassembled into multiple sub-items for approval. The differences in the subjects, conditions, procedures, and procedures involved in the process have led to a long period of approval for the overall project.
Zhang Lei, founder and CEO of Vision, stated that the power market reform has not yet embodied the core value of distributed clean energy. Distributed generation cannot be sold to users who are in need, and many of them can only be used for their own use, and the surplus is sold at a low price to the power grid or discarded, which is not conducive to the clean use of distributed energy and the improvement of energy efficiency. In addition, grid access costs are too high and efficiency needs to be improved. Grid companies still refer to centralized management methods for distributed access. There is no clear process norm and service standard, and there is no time limit for grid-connected services. Lack of special research and technical requirements for distributed wind power grid access standards. Taking a switching station with a cost of nearly RMB 8 million as an example, the cost sharing in a centralized power generation project is not significant, but in a distributed scenario, investors pay too much unnecessary costs.
Therefore, distributed energy requires countries to provide further support from the policy level. Zhang Dongsheng, secretary-general of the China Energy Conservation Association Thermoelectricity Industry Alliance, believes that due to the high price of small gas turbines, photovoltaic modules and energy storage systems used in the distributed energy sector, the construction cost of distributed energy is still high, compared with conventional energy sources, economic efficiency. Relatively poor. Without the support of national fiscal policies, long investment recovery periods will affect investment enthusiasm. Therefore, technological development encouragement, investment incentives and tax incentives, macroeconomic policies of relevant state departments such as power system reforms and thermal system reforms, and regional development policies of local governments are all external environments in which distributed energy applications are indispensable.
In addition to policy support, the development of distributed energy also requires technical support. Due to natural intermittent and random issues, distributed energy sources can easily cause voltage fluctuations and voltage flicker after grid connection. It is a major challenge to achieve power balance in distribution networks and ensure power supply reliability and power quality.
IV. Energy storage and microgrid add new impetus to distributed development
Some energy experts said that to solve the volatility problem of new energy, it is necessary to fully integrate energy storage and other innovative technologies into the microgrid model. Some multinational corporations can solve energy storage problems through advanced technologies, and do a better job of smart microgrids and distributed integrated management, and solve the problems in China's distributed energy development from a technical and business model.
The introduction of energy storage equipment in distributed energy systems will effectively achieve demand-side management, reduce load peak-to-valley differences, and reduce the cost of electricity supply. This will bring about revolutionary changes in traditional energy consumption methods and other aspects. Distributed energy systems are inseparable from energy storage systems. Taking distributed photovoltaic power as an example, although the installed capacity of each unit is not large, the large number still poses a considerable impact on the power grid. To ensure the stability and safety of the power grid, it is necessary to adjust the energy storage devices. In addition, there are thousands of distributed power stations, which have different power generation at different times and at different locations. It is necessary to establish a global energy internet that is free to transfer and intelligently deployed, and to achieve safe and stable power supply. Large-scale energy storage technologies are indispensable.
The "Distributed Energy + Energy Storage" system development and utilization model has received extensive attention. Various countries have introduced policies to support it. The "Distributed Energy + Energy Storage" system is in a rapid development stage, and the combination of energy storage and distribution has begun to significantly reduce the development. The sales volume of the State Grid has caused the phenomenon of “load shedding and net loss” and even “user disconnection”. The promotion of large-scale development of distributed energy and storage energy at the user side can effectively increase the utilization rate of renewable energy sources and reduce the peak load pressure. It is to cope with the increasing volatility at both ends of the current power system, improve the safety and stability of the system, and reduce the system operation adjustment. The cost of an important tool. With the rapid development of energy storage technology and rapid cost reduction, the economics of distributed energy storage regulation at the user side have been superior to the supply side in many cases, and the advantages will become more and more obvious.
Microgrid refers to a small-scale power distribution system composed of distributed power, energy storage devices, energy conversion devices, loads, monitoring and protection devices. A microgrid is an autonomous system that is capable of self-control, protection, and management. It can be operated either in parallel with the external grid or in isolation. The purpose of the microgrid is to realize the flexible and efficient application of distributed power supply and to solve the problem of a large number and diversity of distributed power grids. Microgrid has been widely studied in recent years according to its flexible configuration structure and convenient operation mode. It can improve the safety and reliability of power systems while improving the power quality and power grid service level of users, and promoting renewable energy sources. Distributed generation applications.
Source: China Electric Power News Network
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