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Measures and safeguard measures to improve the flexibility of the power system

with the continuous promotion of the clean transformation of the energy structure and the increase of random fluctuations on the load side, the balance characteristics and methods of the power system are undergoing profound changes, the difficulty of maintaining the system balance is increasing, and the problem of lack of flexible regulation resources is becoming increasingly prominent. During the 13th Five Year Plan period, the installed capacity of new energy in China maintained a rapid growth. By the end of 2019, the installed capacity of wind and solar power in China was 415million kW, nearly 100million kW exceeding the planning target. Comparatively speaking, the flexibility construction of power system lags behind, and the regulation ability of source load links still needs to be further improved

I. construction of power system regulation capacity and analysis of problems

(I) the construction progress of power side regulation capacity is slow

coal power flexibility transformation. By the end of 2019, the "Three North" region has completed about 58 million KW of flexibility transformation units, less than 30% of the planning target. Under the current system and mechanism, the peak shaving income after the flexibility transformation of coal-fired power units is all derived from the cost sharing at the generation side, rather than from the benefit improvement of the whole power system. In addition, the space for coal-fired power generation is compressed, and thermal power enterprises are generally facing losses and are unwilling to actively participate in peak load regulation, which hinders the progress of flexibility transformation of coal-fired power

in terms of natural gas power generation, by the end of 2019, China's installed capacity of gas power has reached 90million kW, accounting for only 4.5% of the total installed capacity of power supply, which is 20million kW lower than the planning target. Among the existing natural gas generating units, more than 90% of the installed capacity is distributed in East China, North China, South China and other regions with less pressure on clean energy consumption. Since the 13th five year plan, China's natural gas supply has been tight, and the growth of natural gas power generation has been slow. The new gas-fired power stations are mainly located in Beijing, Shanghai, Jiangsu, Zhejiang, Guangdong and other regions with strong price affordability

in terms of pumped storage, by the end of 2019, the installed capacity of pumped storage in China has reached 30.29 million KW, accounting for 1.5% of the total installed capacity of power supply, 9 million KW lower than the planned target. According to the latest supervision and examination method of transmission and distribution pricing cost, pumped storage energy is not included in the effective assets of electricity. If it cannot be dredged, the capacity electricity charge will be paid by the provincial power (or regional power) company or by the pumped storage power station itself, which will have a great impact on the operation of pumped storage power station

(II) the role of the power side resource allocation platform has not been brought into full play. The "13th five year plan" is the peak period for the construction of power transmission channels across provinces and regions. By the end of 2019, the national power transmission capacity across provinces and regions has reached 260million kW, and it is expected to reach 280million kW by 2020, basically realizing the national planning goals. The current electricity market transactions in China are mainly based on the "pair" framework agreement between the sending and receiving governments. The consumption of clean energy between the sending and receiving sides is not clear, and it is difficult to effectively balance the interests between regions and different market entities. The consumption of clean energy across provinces and regions is generally faced with the high requirements of the receiving end market for external power curves and prices. It is difficult to reach an agreement on peak shaving demand for a long time, and there is a large room for optimization of the operation curve of cross provincial channels

(III) the potential of demand side participation in system regulation needs to be further tapped

II. The development situation faced by the 14th five year plan

(I) economic and social development needs to improve the regulation capacity of the power system

on the one hand, China's power demand and power supply scale will continue to increase. According to international experience, more flexible regulation power supplies need to be configured. With the improvement of China's urbanization level, industrialization level and power substitution to ensure the quality of products, China's power demand will continue to increase. It is estimated that the power consumption demand of the whole society will reach 9.8 trillion kwh in 2025, and there is still a large demand for power construction during the "14th Five Year Plan". At present, China's power supply structure is dominated by coal-fired power, and the proportion of flexible regulation power supply is only 6%, while the proportion of flexible regulation power supply in the United States, Germany, Spain and other countries is 47%, 19% and 31% respectively, which means that the "14th five year plan" power supply construction needs to focus on the configuration of flexible regulation power supply. On the other hand, China's industrial structure has been gradually transformed from medium and low-end to medium and high-end, and the load peak valley difference will expand accordingly, requiring the construction of more flexible regulated power supplies. Considering that the "14th five year plan" is the stage of China's economy turning to high-quality development, as well as the experience of developed countries such as the United States, Japan and Europe, it is a long-term trend for China's industrial structure to improve from medium and low-end to medium and high-end. The adjustment of industrial structure leads to the continuous increase in the proportion of electricity consumption of the tertiary industry and urban and rural residents. Its power consumption characteristics determine that the peak valley difference rate of the load curve is significantly higher than that of the secondary industry, and the peak valley difference rate of China's power consumption side has a rising trend, The demand for regulatory power supply construction continues to increase

(II) the development of energy and electricity puts forward an urgent demand for the regulation capacity of the power system

"the 14th five year plan" is a critical period for the transformation of clean energy into the main energy, and the power system needs to provide a matching flexible regulation capacity. New energy power generation has randomness and volatility, mostly showing "reverse peak shaving characteristics", which will bring 15% - 30% reverse peak shaving pressure to electricity. In addition, the large-scale replacement of conventional power generation by new energy units makes the overall inertia of the system continuously reduce, and the anti disturbance ability decreases, which is easy to induce the problems of full frequency stability and voltage stability

large scale blackouts in the United States, Britain, Argentina and other countries have brought warnings to the safe operation of electricity in China. When the instantaneous loss of high power occurs in the electric operation, the active power flow shifts in a large range, which may cause the overload of the main section or local equipment, and even lead to the instability of the system power angle, and the surge of active power control pressure, which requires a large flexible power supply to provide fast power backup. Taking the blackout in the UK on August 19, 2019 as an example, the UK national power urgently called the pumped storage power station to balance the system power shortage and prevent the further spread of the accident

(III) comprehensively deepen the reform to provide a good environment for the development of flexible regulation power supply

on the one hand, the reform of power market is conducive to reflect the value of flexible resources. Restoring the commodity attributes of energy and electricity is the core of the power market reform. One of the key points of the power market reform during the "14th five year plan" period is to fully reflect the special attributes of power commodities, let traditional energy and renewable energy give full play to their respective strengths, fairly and fairly safeguard the market interests of all subjects in the market system, and promote the benefits of flexible resources to be fully reflected and utilized in the power system

on the other hand, the reform of mixed ownership injects investment vitality into the flexible regulation of resource development. During the "14th five year plan" period, power enterprises will no longer be the only subject of flexible resource investment in the power system. Flexible resources such as coal and electricity flexibility transformation and pumped storage will attract more social capital and various market entities to invest and jointly participate in the construction and value mining of the power system

(IV) scientific and technological innovation provides a diversified development path for the regulation capacity of the power system

from the power side, achieving electricity friendly development is the development trend of new energy technology. On the one hand, the new energy generation power prediction is developing towards high precision, high resolution, medium and long-term time scale, which will reduce the risk of the uncertainty of the new energy output prediction to the power operation; On the other hand, virtual synchronous machine technology can simulate the characteristics of synchronous generator, such as active frequency modulation and reactive voltage regulation, increase system inertia, improve the stability and safety of wind power and photovoltaic power generation, and prevent disconnection

from the power side, flexible technology and scheduling control technology will further improve the ability of power resource allocation. Flexible DC transmission technology and other electrical flexible technologies can improve the flexible control ability of electricity, realize the rapid and flexible adjustment of power system, improve the stability of power system, and solve the problems of sending end voltage fluctuation, receiving end frequency coefficient reduction and commutation failure; Power dispatching control technology will improve the comprehensiveness, rapidity and accuracy of system operation information, help to tap the potential of load response, and improve the unified consumption level of new energy

from the demand side, digital technology will help transform and upgrade demand side management. The deep integration of digital technology and demand side management can optimize the stock resources and improve the quality of demand side response by changing the traditional regulation mode of "giving instructions"; On the other hand, incremental resources can be mined, and massive decentralized resources can also participate in power system regulation by aggregating user side electric vehicles and distributed energy storage and implementing orderly management

in terms of energy storage, a variety of technology paths will meet the needs of different application scenarios. The complexity of energy storage application scenarios determines that a single energy storage technology cannot meet the diversity of power system needs. Therefore, selecting appropriate energy storage technologies for specific scenarios will be the main theme of the development of energy storage technologies in the future. With the development of utilization demand, superconducting energy storage, flywheel energy storage, supercapacitor and lithium titanate battery are power energy storage technologies, which are suitable for millisecond to minute application scenarios. They can instantly absorb or release energy, provide rapid active support, and avoid system instability. Pumped storage, lithium-ion battery, sodium sulfur battery, compressed air and hydrogen energy storage are energy storage technologies, which are suitable for application scenarios above the hour level. They can reduce the peak valley difference of the system, delay the investment of new generating units and the transformation and upgrading of transmission and distribution

III. key measures to improve the regulation capacity of the power system

(I) key measures for power supply

first, improve the flexible regulation capacity of coal-fired power units. For the existing units, we will continue to promote the flexible transformation. During the "14th five year plan", we will accelerate the transformation of coal-fired power units (about 160million kW) that have not been completed and are clear in the "13th five year plan", and other coal-fired power units can be improved as much as possible. For newly-built units, they are required to have depth regulation capacity, and the minimum technical output is 15% - 25%

second, accelerate the development of pumped storage power stations. It should be no less than the specified value point of cold drawn carpet steel wire grade B, so as to promote the pumped storage project that has been started to be put into operation and play the role of system regulation as soon as possible; Considering the reconstruction of qualified hydropower stations and the construction of hybrid pumped storage power stations, it can become a useful supplement to conventional pumped storage power stations

third, the load center with strong gas price bearing capacity and controlled coal power construction continues to increase gas power construction. North China and East China will provide certain peak shaving support on the basis of meeting the growth of power demand and heat demand

(II) key measures for electricity

at present, cross regional transmission mainly presents the characteristics that the sending end provides regulation capacity for the receiving end, bringing regulation pressure to the sending end areas such as the northwest. During the "14th five year plan" period, we should strengthen unified power dispatching, promote the optimal allocation of flexible resources nationwide, and timely optimize and adjust the power transmission curve when the regulation capacity of the transmission end area is insufficient

(III) demand focused measures

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