Hydroelectric power generation is one of the most mature power generation methods, and it has continuously innovated and developed in the development process of the power system. It has made significant progress in terms of stand-alone scale, technical equipment level, and control technology. As a stable and reliable high-quality regulated power source, hydropower usually includes conventional hydropower stations and pumped storage power stations. In addition to serving as an important supplier of electric power, they have also been playing an important role in peak shaving, frequency modulation, phase modulation, black start, and emergency standby during the entire operation of the power system. With the rapid development of new energy sources such as wind power and photovoltaic power generation, the increase in peak to valley differences in power systems and the reduction in rotational inertia caused by the increase in power electronic equipment and equipment, basic issues such as power system planning and construction, safe operation, and economic dispatch are facing enormous challenges, and are also major issues that must be addressed in the future construction of new power systems. In the context of China’s resource endowment, hydropower will play a more important role in the new type of power system, facing significant innovative development needs and opportunities, and is very important for the economic security of building a new type of power system.
Analysis on the current situation and innovative development situation of hydropower generation
Innovative development situation
The global clean energy transformation is accelerating, and the proportion of new energy such as wind power and photovoltaic power generation is rapidly increasing. The planning and construction, safe operation, and economic scheduling of traditional power systems are facing new challenges and issues. From 2010 to 2021, the global wind power installation maintained a rapid growth, with an average growth rate of 15%; The average annual growth rate in China has reached 25%; The growth rate of global photovoltaic power generation installation in the past 10 years has reached 31%. The power system with a high proportion of new energy is facing major issues such as difficulty in balancing supply and demand, increased difficulty in system operation control and stability risks caused by reduced rotational inertia, and a significant increase in peak shaving capacity demand, resulting in increased system operating costs. It is urgent to jointly promote the resolution of these issues from the power supply, grid, and load sides. Hydroelectric power generation is an important regulated power source with characteristics such as large rotational inertia, fast response speed, and flexible operation mode. It has natural advantages in solving these new challenges and problems.
The level of electrification continues to improve, and the requirements for safe and reliable power supply from economic and social operations continue to increase. Over the past 50 years, the level of global electrification has continued to improve, and the proportion of electric power in terminal energy consumption has gradually increased. Terminal electric energy substitution represented by electric vehicles has accelerated. Modern economic society increasingly relies on electricity, and electricity has become the basic means of production for economic and social operations. Safe and reliable power supply is an important guarantee for modern people’s production and life. Large area power outages not only bring huge economic losses, but also may bring serious social chaos. Power security has become the core content of energy security, even national security. The external service of new power systems requires continuous improvement of the reliability of safe power supply, while internal development is facing a continuous increase in risk factors that pose a serious threat to power security.
New technologies continue to emerge and apply in power systems, significantly improving the degree of intelligence and complexity of power systems. The widespread application of power electronic devices in various aspects of power generation, transmission, and distribution has led to significant changes in the load characteristics and system characteristics of the power system, leading to profound changes in the operating mechanism of the power system. Information communication, control, and intelligence technologies are widely used in all aspects of power system production and management. The degree of intelligence of power systems has significantly improved, and they can adapt to large-scale online analysis and decision support analysis. Distributed power generation is connected to the user side of the distribution network on a large scale, and the power flow direction of the grid has changed from one-way to two-way or even multidirectional. Various types of intelligent electrical equipment are emerging in an endless stream, intelligent meters are widely used, and the number of power system access terminals is increasing exponentially. Information security has become an important source of risk for the power system.
The reform and development of electric power are gradually entering a favorable situation, and the policy environment such as electricity prices is gradually improving. With the rapid development of China’s economy and society, the electric power industry has experienced a huge leap from small to large, from weak to strong, and from following to leading. In terms of system, from government to enterprise, from one factory to one network, to separation of factories and networks, moderate competition, and gradually moving from planning to the market have led to a path of electric power development that is suitable for China’s national conditions. The manufacturing and construction capacity and level of China’s electric power technology and equipment rank among the world’s first-class arrays. The universal service and environmental indicators for electric power business are gradually improving, and the world’s largest and most technologically advanced electric power system has been built and operated. China’s electricity market has been steadily advancing, with a clear path for the construction of a unified electricity market from local to regional to national levels, and has adhered to the China line of seeking truth from facts. Policy mechanisms such as electricity prices have gradually been rationalized, and a electricity price mechanism suitable for the development of pumped storage energy has been initially established, providing a policy environment for realizing the economic value of hydropower innovation and development.
Significant changes have taken place in the boundary conditions for hydropower planning, design, and operation. The core task of traditional hydropower station planning and design is to select a technically feasible and economically reasonable power station scale and operation mode. It is usually to consider hydropower project planning issues under the premise of the optimal goal of comprehensive utilization of water resources. It is necessary to comprehensively consider requirements such as flood control, irrigation, shipping, and water supply, and conduct comprehensive economic, social, and environmental benefit comparisons. In the context of continuous technological breakthroughs and the continuous increase in the proportion of wind power and photovoltaic power, the power system objectively needs to make more full use of hydraulic resources, enrich the operation mode of hydropower stations, and play a greater role in peak shaving, frequency modulation, and leveling adjustment. Many goals that were not feasible in the past in terms of technology, equipment, and construction have become economically and technically feasible. The original one-way mode of water storage and discharge power generation for hydropower stations can no longer meet the requirements of new power systems, and it is necessary to combine the mode of pumped storage power stations to significantly improve the regulatory capacity of hydropower stations; At the same time, in view of the limitations of short-term regulated power sources such as pumped storage power stations in promoting the consumption of new energy sources such as wind power and photovoltaic power generation, and the difficulty of undertaking the task of safe and affordable power supply, it is objectively necessary to increase the reservoir capacity to improve the regulation time cycle of conventional hydropower, in order to fill the gap in system regulation capacity that occurs when coal power is withdrawn.
Innovative development needs
There is an urgent need to accelerate the development of hydropower resources, increase the proportion of hydropower in the new power system, and play a greater role. In the context of the “dual carbon” goal, the total installed capacity of wind power and photovoltaic power generation will reach over 1.2 billion kilowatts by 2030; It is expected to reach 5 billion to 6 billion kilowatts in 2060. In the future, there will be a huge demand for regulating resources in new power systems, and hydropower generation is the most high-quality regulating power source. China’s hydropower technology can develop an installed capacity of 687 million kilowatts. By the end of 2021, 391 million kilowatts have been developed, with a development rate of about 57%, far lower than the 90% development rate of some developed countries in Europe and the United States. Considering that the development cycle of hydropower projects is long (usually 5-10 years), while the development cycle of wind power and photovoltaic power generation projects is relatively short (usually 0.5-1 years, or even shorter) and develops rapidly, it is urgent to accelerate the development progress of hydropower projects, complete them as soon as possible, and play their role as soon as possible.
There is an urgent need to transform the development mode of hydropower to meet the new requirements of peak shaving in new power systems. Under the constraints of the “dual carbon” goal, the future power supply structure determines the enormous requirements of power system operation for peak shaving, and this is not a problem that scheduling mix and market forces can solve, but rather a basic technical feasibility issue. The economic, safe and stable operation of the power system can only be achieved through market guidance, scheduling, and operation control on the premise that technology is feasible. For traditional hydropower stations in operation, there is an urgent need to systematically optimize the utilization of existing storage capacity and facilities, appropriately increase transformation investment when necessary, and make every effort to improve regulation capacity; For conventional hydropower stations newly planned and constructed, it is urgent to consider the significant changes in boundary conditions brought about by the new power system, and plan and construct flexible and adjustable hydropower stations with a combination of long and short time scales according to local conditions. With regard to pumped storage, construction should be accelerated under the current situation where the short-term regulatory capacity is seriously insufficient; In the long run, the system’s demand for short-term peak shaving capabilities should be considered and its development plan scientifically formulated. For water transfer type pumped storage power stations, it is necessary to combine the needs of national water resources for cross regional water transfer, both as a cross basin water transfer project and as a comprehensive utilization of power system regulation resources. If necessary, it can also be combined with the overall planning and design of seawater desalination projects.
There is an urgent need to promote hydropower generation to create greater economic and social value while ensuring the economic and safe operation of new power systems. Based on the development goal constraints of carbon peak and carbon neutrality in the power system, new energy will gradually become the main force in the power supply structure of the future power system, and the proportion of high carbon power sources such as coal power will gradually decrease. According to data from multiple research institutions, under the scenario of large-scale withdrawal of coal power, by 2060, China’s installed capacity of wind power and photovoltaic power generation accounted for about 70%; The total installed capacity of hydropower considering pumped storage is about 800 million kilowatts, accounting for about 10%. In the future power structure, hydropower is a relatively reliable and flexible and adjustable power source, which is the cornerstone of ensuring the safe, stable and economic operation of new power systems. It is urgent to shift from the current “power generation based, regulation supplemented” development and operation mode to “regulation based, power generation supplemented”. Accordingly, the economic benefits of hydropower enterprises should be brought into play in the context of greater value, and the benefits of hydropower enterprises should also significantly increase the revenue from providing regulation services to the system based on the original power generation revenue.
There is an urgent need to carry out innovation in hydropower technology standards and policies and systems to ensure the efficient and sustainable development of hydropower. In the future, the objective requirement of new power systems is that the innovative development of hydropower must be accelerated, and the existing relevant technical standards, policies, and systems also urgently need to be corresponding to the innovative development to promote the efficient development of hydropower. In terms of standards and specifications, it is urgent to optimize standards and specifications for planning, design, operation and maintenance based on pilot demonstration and verification in accordance with the technical requirements of the new power system for conventional hydropower stations, pumped storage power stations, hybrid power stations, and water transfer pumped storage power stations (including pumping stations), in order to ensure the orderly and efficient development of hydropower innovation; In terms of policies and systems, there is an urgent need to study and formulate incentive policies to guide, support, and encourage the innovative development of hydropower. At the same time, there is an urgent need to make institutional designs such as market and electricity prices for the conversion of new values of hydropower into economic benefits, and encourage enterprise entities to actively carry out innovative development technology investment, pilot demonstration, and large-scale development.
Innovative development path and prospect of hydropower
The innovative development of hydropower is an urgent need to build a new type of power system. It is necessary to adhere to the principle of adapting measures to local conditions and implementing comprehensive policies. Different technical schemes should be adopted for different types of hydropower projects that have been built and planned. It is necessary to consider not only the functional needs of power generation and peak shaving, frequency modulation, and equalization, but also the comprehensive utilization of water resources, adjustable power load construction, and other aspects. Finally, the optimal scheme should be determined through comprehensive benefit evaluation. By improving the regulation capacity of conventional hydropower and constructing comprehensive interbasin water transfer pumped storage power stations (pumping stations), there are significant economic benefits compared to newly built pumped storage power stations. Overall, there are no insurmountable technical barriers to the innovative development of hydropower, with huge development space and outstanding economic and environmental benefits. It is worth paying high attention to and accelerating large-scale development based on pilot practices.
“Power generation+pumping”
The “power generation+pumping” mode refers to utilizing hydraulic structures such as existing hydropower stations and dams, as well as power transmission and transformation facilities, to select suitable locations downstream of the hydropower station’s water outlet to build a water diversion dam to form a lower reservoir, add pumping pumps, pipelines, and other equipment and facilities, and use the original reservoir as the upper reservoir. On the basis of the original hydropower station’s power generation function, increase the pumping function of the power system during low load, and still use the original hydraulic turbine generator units for power generation, In order to increase the pumping and storage capacity of the original hydropower station, thereby improving the regulating capacity of the hydropower station (see Figure 1). The lower reservoir can also be constructed separately at a suitable location downstream of the hydropower station. When constructing a lower reservoir downstream of the water outlet of a hydropower station, it is advisable to control the water level so as not to affect the power generation efficiency of the original hydropower station. Considering the optimization of operation mode and the functional requirements for participating in leveling, it is advisable for the pump to be equipped with a synchronous motor. This mode is generally applicable to the functional transformation of hydropower stations in operation. The equipment and facilities are flexible and simple, with the characteristics of low investment, short construction period, and quick results.
“Power generation+pumped power generation”
The main difference between the “power generation+pumping power generation” mode and the “power generation+pumping” mode is that changing the pumping pump into a pumped storage unit directly increases the pumped storage function of the original conventional hydropower station, thereby improving the regulatory capacity of the hydropower station. The setting principle of the lower reservoir is consistent with the “power generation+pumping” mode. This model can also use the original reservoir as a lower reservoir and build an upper reservoir at a suitable location. For new hydropower stations, in addition to installing certain conventional generator sets, pumped storage units with a certain capacity can be installed. Assuming that the maximum output of a single hydropower station is P1 and the increased pumped storage power is P2, the power operation range of the power station relative to the power system will be expanded from (0, P1) to (- P2, P1+P2).
Recycling of cascade hydropower stations
Cascade development mode is adopted for the development of many rivers in China, and a series of hydropower stations, such as Jinsha River and Dadu River, are constructed. For a new or existing cascade hydropower station group, in two adjacent hydropower stations, the reservoir of the upper cascade hydropower station serves as the upper reservoir and the lower cascade hydropower station serves as the lower reservoir. According to the actual terrain, appropriate water intakes can be selected, and development can be carried out by combining the two modes of “power generation+pumping” and “power generation+pumping power generation”. This mode is suitable for the reconstruction of cascade hydropower stations, which can significantly improve the regulation capacity and regulation time cycle of cascade hydropower stations, with significant benefits. Figure 2 shows the layout of a hydropower station developed in a cascade of a river in China. The distance from the dam site of the upstream hydropower station to the downstream water intake is basically less than 50 kilometers.
Local balancing
“Local balancing” mode refers to the construction of wind power and photovoltaic power generation projects near hydropower stations, and the self adjustment and balancing of hydropower station operations to achieve stable power output in accordance with scheduling requirements. Considering that the main hydropower units are all operated according to the power system dispatching, this mode can be applied to radial flow power stations and some small hydropower stations that are not suitable for large-scale transformation and are usually not scheduled as conventional peak shaving and frequency modulation functions. The operation output of hydropower units can be flexibly controlled, their short-term regulation capacity can be exploited, and local balance and stable power output can be achieved, while improving the asset utilization rate of existing transmission lines.
Water and power peak regulation complex
The mode of “water regulation and peak power regulation complex” is based on the construction concept of water regulation pumped storage power stations, combined with major water conservancy projects such as large-scale interbasin water transfer, to construct a batch of reservoirs and diversion facilities, and to use the head drop between reservoirs to construct a batch of pumping stations, conventional hydropower stations, and pumped storage power stations to form a power generation and storage complex. In the process of transferring water from high altitude water sources to low altitude areas, the “Water Transfer and Power Peak shaving Complex” can fully utilize the head drop to obtain power generation benefits, while achieving long-distance water transfer and reducing water transfer costs. At the same time, the “water and power peak shaving complex” can serve as a large-scale dispatchable load and power source for the power system, providing regulation services for the system. In addition, the complex can also be combined with seawater desalination projects to achieve comprehensive application of water resource development and power system regulation.
Seawater pumped storage
Seawater pumped storage power stations can choose a suitable location on the coast to build an upper reservoir, using the sea as the lower reservoir. With the increasingly difficult location of conventional pumped storage power stations, seawater pumped storage power stations have received the attention of relevant national departments and have conducted resource surveys and forward-looking technical research tests. Sea water pumped storage can also be combined with the comprehensive development of tidal energy, wave energy, offshore wind power, etc., to build large storage capacity and long regulation cycle pumped storage power stations.
Except for run-of-river hydropower stations and some small hydropower stations with no storage capacity, most hydropower stations with a certain reservoir capacity can study and carry out pumped storage function transformation. In the newly built hydropower station, a certain capacity of pumped storage units can be designed and arranged as a whole. It is preliminarily estimated that the application of new development methods can quickly increase the scale of high-quality peak shaving capacity by at least 100 million kilowatts; Using the “water regulation and power peak shaving complex” and seawater pumped storage power generation can also bring extremely significant high-quality peak shaving capacity, which is of great significance for the construction and safe and stable operation of new power systems, with significant economic and social benefits.
Suggestions for hydropower innovation and development
First, organize the top-level design of hydropower innovation and development as soon as possible, and issue guidance to support the development of hydropower innovation and development based on this work. Conduct research around major issues such as the guiding ideology, development positioning, basic principles, planning priorities, and layout of hydropower innovative development, and on this basis prepare development plans, clarify development stages and expectations, and guide market entities to orderly carry out project development.
The second is to organize and carry out technical and economic feasibility analysis and demonstration projects. In combination with the construction of new electric power systems, organize and carry out resource surveys of hydropower stations and technical and economic analysis of projects, propose engineering construction plans, select typical engineering projects to carry out engineering demonstrations, and accumulate experience for large-scale development.
Third, support the research and demonstration of key technologies. By setting up national science and technology projects and other means, we will support fundamental and universal technical breakthroughs, key equipment development, and demonstration applications in the field of hydropower innovation and development, including but not limited to blade materials for seawater pumping and storage pump turbines, and survey and design of large-scale regional water transfer and power peak shaving complexes.
Fourth, formulate fiscal and tax policies, project approval, and electricity pricing policies to promote the innovative development of hydropower. Centering on all aspects of the innovative development of hydroelectric power generation, policies such as financial interest discounts, investment subsidies, and tax incentives should be formulated in accordance with local conditions in the early stages of the project development, including green financial support, to reduce the financial costs of the project; For pumped storage renovation projects that do not substantially change the hydrological characteristics of rivers, simplified approval procedures should be implemented to reduce the administrative approval cycle; Rationalize the capacity electricity price mechanism for pumped storage units and the electricity price mechanism for pumped power generation to ensure reasonable value returns.
Post time: Mar-22-2023
