Recently, the State Administration for Market Regulation (National Standardization Administration) released a batch of proposed standards for public notice. Three of them are related to energy storage. They are “Technical Specifications for Electrochemical Energy Storage Grid-Type Converters”, “Guidelines for Safety Evaluation of Electrochemical Energy Storage Power Stations”, and “Flywheel Energy Storage Converters for Power Energy Storage”.
Technical Specifications for Electrochemical Energy Storage Grid-connected Converters
The main drafting units are China Electric Power Research Institute Co., Ltd., Sungrow Power Supply Co., Ltd., and Huawei Digital Energy Technology Co., Ltd.
The standard specifies the classification and coding, basic requirements, functional requirements, performance requirements and auxiliary system requirements of electrochemical energy storage grid-type converters, describes the corresponding test methods, and specifies the inspection rules, marking, packaging, transportation and storage. It is applicable to the design, manufacture, testing, inspection, operation, maintenance and overhaul of grid-type converters with AC port voltage of 35kV and below.
Purpose and significance: The “double high”, “double peak” and “double random” characteristics of the current power system are becoming increasingly prominent, which puts forward higher requirements for the regulation and control of the power grid. As a high-quality flexible regulation resource and potential active support means, energy storage is an important equipment foundation and key technology for building a new energy system and promoting the green and low-carbon transformation of energy. It is an important support for achieving the goal of “carbon peak and carbon neutrality”. It can play a significant role in the challenges of “ensuring supply, ensuring safety and promoting consumption” in the new power system, and has achieved engineering and commercial applications.
With the continuous increase in the proportion of new energy, the local high-proportion new energy access to the power grid lacks synchronous support power supply, the short-circuit current level continues to decline, showing the characteristics of a weak AC power grid, broadband oscillation, transient overvoltage, phase-locked out of step and other new energy grid-connected stability problems are relatively frequent, and the safety and stability of the power system is becoming more and more prominent.
Compared with traditional energy storage technology that uses grid-following phase-locked loop control technology, grid-building energy storage technology can simulate the excitation and power angle characteristics of the generator, and has active voltage support, automatic inertia support and frequency regulation response capabilities. It can improve the damping characteristics of the power grid to suppress broadband oscillations and improve the short-circuit capacity of weak power grids. It is an effective means to solve the stable operation of new power systems and the high-proportion consumption of new energy.
The “National Energy Administration’s Notice on Organizing and Carrying out Pilot Demonstrations of Renewable Energy Development” (Guoneng Fa Xinneng [2023] No. 66) clearly states that it mainly supports grid-based wind power, grid-based photovoltaic power generation, and grid-based energy storage. , new energy low-frequency network transmission and other technology research and development and engineering demonstrations, significantly improving the voltage, frequency and other stable support capabilities of new energy access to weak power grids, and greatly improving the safe and stable power transmission capabilities of the transmission channels of large wind power and photovoltaic base projects.
Xinjiang, Tibet, Jiangsu and other provinces and cities have successively proposed to install grid-based energy storage devices and build grid-based energy storage power stations to cope with the risks of new power systems, improve the grid’s anti-interference, active support, perception and other network-related capabilities, and promote the transformation of new energy from grid connection to networking.
However, at present, there are no clear standards for grid-type energy storage inverters in China. Therefore, in the process of designing, building and connecting to the grid of grid-type energy storage power stations, it is impossible to carry out reliable and safe boundary design of grid-type inverters, it is impossible to carry out product type testing, and it is impossible to ensure the safe and reliable operation of grid-type energy storage power stations. Therefore, in order to adapt to the actual needs of the project and the needs of future technological development, it is necessary to put forward technical requirements for grid-type inverters, clarify the test methods, clarify the capacity boundaries, point out the direction for the development of the industry, improve the level of energy storage equipment, and help energy storage equipment go global as soon as possible and seize the high ground of technology.
Guidelines for Safety Assessment of Electrochemical Energy Storage Power Stations
The main drafting unit is China Electric Power Research Institute Co., Ltd.
The standard is applicable to the safety evaluation of electrochemical energy storage power stations with installed capacity of 500kW/500kWh and above, such as lithium-ion batteries, sodium-ion batteries, lead-acid (carbon) batteries, etc. It stipulates the evaluation contents and methods of safety production rules and regulations evaluation, equipment and facility evaluation, operation and maintenance evaluation, overhaul evaluation and comprehensive evaluation of electrochemical energy storage power stations.
Purpose and significance: (I) Necessity and feasibility of formulating and revising recommended national standards (1) Necessity of project establishment: As a key technology supporting the development of smart grid and energy transformation, energy storage has received extensive attention. Among them, battery energy storage represented by lithium-ion batteries has become one of the preferred storage carriers for large-scale energy storage.
In recent years, lithium-ion battery energy storage technology has continued to improve in key technical areas such as body research and development, large-scale integration, safety protection, function realization and engineering verification. It has passed the large-scale application function verification, and the technical standard system and application management system for power system applications are becoming increasingly perfect. Problems in controllable and safe applications are also gradually improving.
However, as the scale of battery energy storage applications gradually increases, many problems and risks in the quality and safety of energy storage systems have been exposed, which are specifically manifested in two aspects: First, safety issues are prominent. In recent years, many safety accidents have occurred in energy storage power stations at home and abroad. The reasons involve defects in the core components of energy storage, external excitation sources, operating environment and management defects. Second, reliability is insufficient. Most of the energy storage power stations that have been put into operation have problems such as insufficient capacity, low efficiency, rapid life decay, frequent failures, etc., which seriously affect the normal operation of the power station and also bring certain hidden dangers to safe and economical dispatching and operation.
The root cause of the above problems is that the construction of energy storage projects has not strictly implemented technical standards and requirements, lacks systematic closed-loop technical supervision requirements, and cannot form an effective safety supervision assessment of energy storage power stations.
Therefore, in response to the current situation of the lack of safety assessment standards for electrochemical energy storage power stations, it is urgent to start from the four aspects of safety production regulations and system evaluation, equipment and facility evaluation, operation and maintenance evaluation, and maintenance evaluation. The necessary evaluation and supervision of the entire process of energy storage planning and design, equipment selection, supervision, arrival sampling, installation, commissioning, trial operation, grid connection acceptance, and maintenance should be carried out to improve the quality and safety level of energy storage equipment and reduce the probability of accidents in energy storage power stations, so as to give full play to the comprehensive effectiveness of electrochemical energy storage in supporting the efficient and economic operation of the power grid.
(2) Project feasibility: 1) Policy requirements.
After the “4.16 Energy Storage Power Station Fire and Explosion Accident” in Beijing, the State Council’s Work Safety Committee Office, the National Energy Administration, the National Development and Reform Commission, etc. have all issued relevant policies and regulations to clearly strengthen the quality and safety management of energy storage.
The formulation of safety assessment specifications for energy storage power stations is a response to the above policy requirements.
2) Industrial development and technological maturity.
With the large-scale commissioning of electrochemical energy storage power stations, there are long-term major safety hazards in existing energy storage power stations, and there is a risk of “grid-connected with problems” in newly built energy storage power stations. It is necessary to establish a safety evaluation procedure for energy storage power stations, cooperate with on-site inspections, evaluate the safety risks of existing and newly built energy storage power stations, and propose rectification measures to provide a safety basis for the commissioning and stable operation of energy storage power stations.
3) Have extensive experience in standard formulation.
China Electric Power Research Institute has taken the lead in compiling dozens of national standards, industry standards, enterprise standards, and group standards in the field of electric energy storage, including GB/T 42288 “Safety Regulations for Electrochemical Energy Storage Power Stations”. It has been deeply engaged in research related to electric energy storage for many years and has the experience and ability to formulate and write standards.
4) Have key technical support.
The application team has undertaken a number of scientific research projects related to the field of energy storage safety, and has carried out safety assessments of multiple energy storage power stations in Jiangsu, Shanghai and other places. It has a rich theoretical and practical research foundation and can provide strong support for the formulation of this standard.
《Flywheel Energy Storage Converter for Power Energy Storage》
The main drafting units are Zhuzhou National Engineering Research Center for Converter Technology Co., Ltd., China Electric Power Research Institute Co., Ltd., and Huachi Kinetic Energy (Beijing) Technology Co., Ltd. The standard applies to the design, manufacture, testing, inspection, operation, maintenance and overhaul of flywheel energy storage converters that use flywheels as energy storage carriers in power systems.
The standard specifies the functional requirements of flywheel energy storage converters for electric energy storage, such as braking, online input, power control, alarm and protection, communication, operation information monitoring, and performance requirements such as electrical performance and safety performance. It describes the corresponding test methods, and specifies the classification and coding, normal working conditions, grid-connected operation electrical conditions, cabinet requirements and protection levels, inspection rules, marking, packaging, transportation and storage.
Purpose and significance: The current trend of carbon neutrality is accelerating, and the installed capacity and power generation of new energy are developing rapidly. However, when a large number of new energy sources are integrated into the power grid, the fluctuation of the power grid will increase, and the security of the power grid may be impacted. Therefore, the rigid demand for power grid frequency regulation is highlighted.
Flywheel energy storage uses the kinetic energy of a rotating body during high-speed rotation to achieve energy storage, and realizes the conversion of electrical energy and kinetic energy by controlling the flywheel. It has the characteristics of high power density, no restrictions on the number of charge and discharge times, rapid charge and discharge, green and pollution-free, and long service life. It has unique advantages in rapid load regulation of power systems, and is especially suitable for primary frequency regulation applications of power grids. The number of charge and discharge times per day can be as high as hundreds or thousands. With the large-scale grid connection of new energy, the frequency fluctuations of the power grid are becoming increasingly larger, and there is an urgent need for short-term and high-frequency energy storage technology support such as flywheel energy storage.
Flywheel energy storage converter is the key equipment to achieve safe and reliable grid connection of flywheel.
In the application of grid frequency modulation, the flywheel system receives the dispatching instructions of the grid, controls the power of the flywheel energy storage converter, and realizes rapid energy response.
At present, the application of flywheel energy storage converter in the field of power energy storage lacks standard specifications and guidance, and it is urgent to formulate relevant national standards.
Necessity (I): The technical development of power-level flywheel energy storage bidirectional converter urgently needs standard guidance. At present, there is no unified standard for the technical scheme and technical indicators of flywheel energy storage converter, which leads to the diversification of converter schemes in actual project applications, and cannot fully meet the key technical indicators such as rapid charge and discharge response, regulation, switching, and safety and reliability requirements of flywheel in power energy storage.
Therefore, it is necessary to formulate national standards in combination with the actual application needs of power energy storage, guide the technical development direction of flywheel energy storage converter dedicated to energy storage, and improve its comprehensive application performance.
Necessity (II): The need to regulate the high-quality development of the industry From 2022, flywheel energy storage for power energy storage will enter the stage of large-scale application, and MW-level flywheel energy storage power stations will continue to be built. Faced with the growing application scale, the application of flywheel energy storage converters in the field of power energy storage lacks standard specifications and guidance. It is urgent to formulate national standards based on the actual application needs of power energy storage and the characteristics of flywheel energy storage, clarify the technical requirements for flywheel energy storage converters, propose test methods that match the actual operating conditions and needs of flywheel energy storage systems, and regulate the development of the flywheel energy storage converter industry.
Necessity (III): Improve the national standard system for power energy storage Fill the gap in the national standard for flywheel energy storage converters in the power energy storage standard system.
(2) Project feasibility: 1) Industrial development and technical maturity.
Flywheel energy storage is a new energy storage technology with increasingly mature technology. As a result, flywheel energy storage converters have also developed rapidly and are in the stage of rapid development from demonstration project application to commercial scale. Currently, there are MW-level grid-connected demonstration projects.
As the scale of new energy grid connection gradually expands, the application of flywheel energy storage to solve the problem of grid frequency regulation has become the preferred solution.
However, there is no national standard specifically for flywheel energy storage converters for power energy storage at home and abroad, especially for single-machine high-power MW-level flywheel energy storage, which has just started. There is no reference standard for its supporting flywheel energy storage bidirectional converter, which cannot fundamentally guarantee the safety and quality of the stable operation of the flywheel energy storage system. The formulation of this standard can provide effective guarantee for the safety and quality of flywheel energy storage power stations.
2) Have rich experience in standard compilation.
The application team is the IEC/TC9 international standard, the National Traction Standardization Committee (SAC/TC278) and the industry traction electrical equipment standardization unit, and has obtained the leading drafting rights of 5 important international standards, and organized the formulation of a total of 139 national and industry standards.
3) Have rich theoretical and practical support.
The application team is the only national engineering research center in the field of medium and large power conversion technology in China, specializing in cutting-edge scientific research, modular design, and systematic application of core technologies in conversion technology.
Relying on the core technology and platform of rail transit, a complete industrial chain from devices, equipment to systems has been established. The overall technology is leading in China, and a series of first-set performance breakthroughs have been achieved, achieving import substitution in the field of major technical equipment and breakthroughs in key “neck” technologies.
At the same time, the application team has rich experience in the development and application of flywheel energy storage converter products in the field of power frequency regulation.
