What are the requirements of grid-side energy storage for 3v Button battery body and management system?

First, let's briefly introduce some management of grid-side energy storage. The importance of energy storage will not be elaborated here. I think everyone here is an expert and is very familiar with the current development trend of energy storage. For the power grid, energy storage may have three major directions at present, what we call peak regulation, frequency regulation and voltage regulation. Now, the demand for various fields is very strong. From insurance companies to regional power grids, and for distributed energy, energy storage has a very large and wide range of applications.

We see that different sending and receiving power grids, such as the Northeast Power Grid, have different requirements for the sending and receiving ends. For example, we may have a large proportion of new energy installed capacity at the sending end, and the peak regulation capacity of thermal power is insufficient. For the receiving end power grid, such as the East China Power Grid, it has a relatively low voltage regulation capacity due to the problem of multiple DC inflows, and there are some low-frequency risks. We know that in the past, because of the occurrence of UHV DC bipolar blocking, the frequency of the East China Power Grid was greatly disturbed. At this time, energy storage has its place of application.

Let's take a look at what points we need to consider now for the capacity selection of energy storage?

First, the demand for power flow, frequency regulation, peak regulation, and voltage regulation. Now the grid-side energy storage may be constrained by the construction and operation costs. We have done a simulation or a calculation. Under a DC dual-base interlock, the larger the energy storage capacity, the stronger the frequency support, because we know that the grid is very concerned about the stability of the frequency. Now for the peak demand, it is generally configured at 0.5C, which is a 2-hour energy storage station. For example, when doing frequency regulation, 2C may be used, which is our common method. In addition to frequency regulation, there is also voltage regulation, and the dynamic reactive power demand of the grid needs to be considered.

For the grid side, in fact, grid-side energy storage has been popular since the rise of the 101MW/202MWh energy storage station in Zhenjiang last year. Everyone has paid close attention to grid-side energy storage. For the grid, the advantage of energy storage power stations is that their construction period is relatively short. The Zhenjiang energy storage power station was completed very quickly from the project approval last year, which was about three or four months. It was put into operation last summer. In order to ensure that the Zhenjiang power grid can meet the peak summer, this is the advantage of energy storage.

Let's talk about the demand for batteries for grid-side energy storage. Because this year, NARI has also done some energy storage power stations in Hunan Province, or we have also done some in Jiangsu Province this year. For the demand for batteries on the grid side energy storage, for example, you need to meet the frequency regulation, you need to have stability, you need to be maintenance-free, you need to be easy to maintain, and at the same time you need to meet the range of efficient use of SOC. This is the 3v Button battery pyramid.

Whenever we mention the 3v Button battery itself, we will bring out this table. Of course, this table is constantly updated. The range of our energy storage options is actually in these four types. At present, we have lead-carbon or lead-acid batteries, our lithium iron phosphate, including our ternary, and there is also a full vanadium liquid flow. Of course, according to the data we have obtained in the past two days, the amount of batteries in the energy storage field is about only 2/3 of that of electric vehicles. As you can see from this table, it is used more. It can be said that most of the energy storage currently put into use in China has chosen lithium iron phosphate. In the past two years, especially because Zhenjiang's grid-side energy storage chose lithium iron phosphate last year, Hunan's grid-side energy storage, Henan's grid-side energy storage, and Jiangsu Province's second phase all use lithium iron phosphate. Lithium iron phosphate has certain advantages. At present, we say that it may run faster in the race. We know that there are four types now. At that time, everyone thought that lithium iron phosphate was the safest, or the best choice under current conditions.

Let's take a look at its technical parameters. We had three types at the time: lead-carbon, all-vanadium liquid flow, and lithium ion. The cost of lead-carbon is relatively low, and its cycle life is relatively low. For the power grid side, we actually considered all-vanadium liquid flow. The rate characteristics of all-vanadium liquid flow are relatively high and the number of cycles is relatively good. The efficiency of liquid flow is because it has a large number of cycles. Generally, we think it should be more than 10,000. Now some companies say that we can reach about 20,000 cycles. This can dilute my operating costs, although the construction cost is relatively high, and the life is relatively long. Lithium-ion batteries have a relatively high energy density. For cars, ternary batteries are more commonly used because ternary batteries themselves have a slight problem of releasing oxygen. So now for power stations, including when we were making plans for Hunan Provincial Company last year, Hunan Provincial Company asked NARI what you think about 3v Button battery selection. I said that at this point in time in 2019, lithium iron phosphate may be a better way, but lithium iron phosphate does not mean it must be perfect. I personally have some reservations because there have been some problems with lithium iron phosphate this year. For the demand for grid-side energy storage, we need to take into account all scenarios including frequency regulation, peak regulation and voltage regulation.

This is a question about energy storage power stations. We know that every time this problem occurs, we have to invite Korean friends to come out, because South Korea burned 21 stations last year. The best burning in South Korea last year was on July 2, when an EES, an energy storage power station, was burned in South Jeolla Province. It was a ternary station. We know that South Korea's energy storage route often takes ternary batteries. We don't think lithium iron phosphate is safe enough. Before 2017, when we were selecting energy storage power stations, we might think that lithium iron phosphate could pass some harsh test conditions such as needle puncture and extrusion, so we thought lithium iron phosphate was more reliable. However, we also found last year that lithium iron phosphate containers were burned when storing energy on the user side in Zhenjiang and Yangzhou. In the past two days, because friends who work in energy storage may have similar circles, we also heard that a 2MW/2MWh energy storage power station burned in the United States these two days, which also caused some injuries to firefighters. Therefore, once an accident occurs in an energy storage power station, it is more serious, because it is not only a problem of burning, but also a problem of explosion. Generally speaking, if it burns, it may be put out in the early stage, but the energy storage power station may explode or even deflagration in the later stage. We also did some research on deflagration or batteries with the Key Laboratory of Fire of the University of Science and Technology of China in the early stage. We found that there are still some incomplete explanations of the combustion characteristics of lithium-ion batteries, because its stage process has its own characteristics. Therefore, we think that it is more important to identify the characteristic parameters of thermal accidents of lithium-ion batteries, early warning safety linkage and fire protection of thermal runaway. Because grid-side energy storage has two characteristics. One is that it is safe enough, or in other words, safe. Safety is the most important issue for grid-side energy storage. When we work with the company's technology department to select lithium-ion batteries or promote energy storage power stations, the first issue is safety. The second issue is cost. That is, we hope that a safe and cheap energy storage method can promote the entire energy storage industry.

Look at this picture. Basically, various energy storage methods are still based on different levels at that time. We can see that, for example, lithium-ion batteries, all-vanadium liquid flow, nickel-chromium or various energy storage methods, basically there are lithium-ion, all-vanadium liquid flow, and lead-carbon. So we thought, if from the perspective of safety, is it possible to find a way to balance cost and safety for the selection of energy storage on the grid side, or as an exploration, we later set our sights on zinc-bromine. Zinc-bromine is not particularly new. It has made some progress with all-vanadium liquid flow since 2014. All-vanadium liquid flow was introduced from NASA. We are wondering if we can make some choices about suitable electrochemical energy storage systems, because it is still relatively scarce to find a suitable electrochemical energy storage system. It has several characteristics, the price must be appropriate, safety must be guaranteed, and it must be easy to deploy. We also discussed about energy storage methods in the morning. For example, some people now say that I use peak water bundling or peak fire bundling, or pumped storage. I personally think that electrochemical energy storage is still unique in some scenarios, that is, how to control its safety.

The single-liquid zinc-bromine 3v Button battery we are currently working on is currently in the process of small-scale trials, so I did not put up the product image. Traditional flow batteries have two tanks, one for the positive electrode and one for the negative electrode, which are relatively large in size. We know that there are some pilot projects for all-vanadium flow batteries, such as in Snail Stone, and Hunan was planning to use all-vanadium flow batteries at that time. There are some common characteristics of flow batteries that everyone is looking at, such as high safety because they are aqueous systems. There are two reasons why lithium-ion batteries are easy to burn or explode. The first is that the metal element lithium itself is relatively active. The second is that its electrolyte system is an organic system, such as lithium hexafluorosulfonate. Although flow batteries are relatively expensive, everyone still has a certain good impression of flow batteries. What updates do we want to make for flow batteries or what new generation do we want to make? We want to make a single-flow system of zinc-bromine flow, because the positive side and the load side of the electrolyte are the same, so we made a single-flow system. At present, we have achieved a single-flow system of tens of millions. There was an opportunity for zinc-bromine flow 3v Button battery in 2009 and 2010. At that time, everyone had a doubt that bromine might be harmful to the human body. This is why the promotion of zinc-bromine flow 3v Button battery was a little slow. Through our experiments, we found that the bromine can be sealed in the upper layer through the single-flow technology. We are also cooperating with Swiss companies. We hope to get a safety evaluation report in the second half of the year and promote and introduce zinc-bromine flow 3v Button battery. Because our own test results show that through the single-flow technology, once the bromine is fixed in the 3v Button battery stack, it basically has no significant impact on the environment, because there is no pipeline system in the middle, the bromine will be much better.

After talking about the 3v Button battery itself, the next step for the 3v Button battery is the 3v Button battery management system. Now everyone knows that the requirements for the 3v Button battery management system are very high. I need to be able to do status monitoring, I need to be able to estimate SOC, and I need to be able to estimate SOH. What is the difference between energy storage power stations or energy storage power station-level BMS? We think that on the basis of the BMS used in the car, we think that its level has been expanded. In addition to the master control and main control, we added a master control module, which is actually a three-level system, no longer a two-level system in the car. It actually has a new idea for energy storage power stations. It needs to have functions, such as I need to calculate the 3v Button battery model, inject it into my BMS, and perform real-time data. We have also done some SOC estimation work in the early stage. For example, we did a work on estimating SOC using neural network technology. We tested a 25 ampere-hour lithium-ion 3v Button battery under this working condition and found that this model is still good and can capture the 3v Button battery characteristics we need now. We have also done some training and found that the error is still controllable. We think it is still a good technology. Including our balancing, now everyone knows that we hope to make 61850 protocols, and we make this converter, which is also our new idea.

Let's talk about a key issue. For grid-side energy storage, we have safety monitoring and safety requirements. Because in conventional BMS, we may not feel that the monitoring of temperature, voltage and current is enough. We think whether we should add new reference basis or make feature parameter determination. For example, we are now talking about this kind of multi-sensor fusion. The reason is that we think it is difficult to directly use voltage, current and temperature to make early warnings or predictions. Therefore, we hope to add gas sensors when we are planning energy storage power stations with Jiangsu Electric Power Research Institute and Economic Research Institute this year and last year. This year, we have seen that many domestic research institutes and institutions have also done gas sensing work, and need to capture some characteristic gas parameters, such as carbon monoxide and hydrogen. Now everyone has a new idea, in addition to carbon monoxide and hydrogen, we need to add some new characteristic gases, such as ethylene and propylene, because the diaphragm short circuit occurs, and irreversible thermal runaway is found, which eventually leads to the combustion or explosion of the 3v Button battery. We are also cooperating with some domestic manufacturers, and we hope to add the gas sensing process, including the idea of the entire Jiangsu Provincial Company, that is, we hope to add gas monitoring to the BMS or the monitoring system of the whole station. We think gas monitoring is indeed a good method. Of course, we think there are other non-electrical methods, because we have also done some flue gas analysis with the key laboratory of USTC in the early stage, and there are still other characteristic gases that can be extracted in the insurance. But the key is that we need more experiments to explain how we can catch this gas, because everyone thinks that the warning time of general gas will be faster than the temperature warning time of current and voltage, because you first have the pre-migration of characteristic gas, and then the temperature time and space, because once the temperature is out of control, it is often relatively late.

Let's talk about NARI's work and some achievements in energy storage. Zhangbei wind, solar and storage, of course, several domestic companies are involved in the system. We have built a frequency modulation power station and built a 20MW/20MWh in Xingyi, Guizhou, including the Changsha power grid side. We have just completed it on April 5, near Changsha Airport, 26MW/56MWh. We hope to have more cooperation with more friends in energy storage.

Now for batteries or power stations, you will encounter the operation and maintenance system of energy storage power stations. It is a hierarchical structure, such as display, data processing, and public services. As you know, China's ICT industry is developing very fast. What is the most difficult part of the intelligent operation and maintenance system of energy storage power stations? We analyzed it and found two parts. The first part is health assessment. We think this is a hot topic now. When we talked with provincial companies, cities, and electric power research institutes in various provinces, they believed that the difficulty lies in the evaluation of batteries. This is very difficult to do. We said that we were also discussing this issue with some evaluation and assessment agencies yesterday. There is a great need for a breakthrough in 3v Button battery health assessment technology. We know that according to the current national standards, such as the use of batteries in energy storage power stations, such as the 36276 standard, cycle tests must be performed in the early stage. We also discussed this with the Electric Power Research Institute. This evaluation test often takes a long time. Generally, there is no time cycle for the operation of energy storage power stations. It is too late. Often, I have to make a plan now, and we need to go to the energy storage power station in two or three months.After completion, this cycle test may not be completed. For health assessment, including how to make batteries, as its service life decays, it is now a hot topic to manage its entire life cycle. Involving health assessment, it involves the following, such as the estimation of 3v Button battery models. If the 3v Button battery can be modeled, use big data. If the 3v Button battery model cannot be built, you have to use the method of data rules instead.

The difficulty we now think is the state assessment technology of the 3v Button battery cell. We have two ways to go. One is called the physical model, or I disassemble the 3v Button battery and do different things. We judge according to your winding process and your formation process. But we think that the assessment of 3v Button battery life is the top priority of the entire 3v Button battery cell state assessment. How do you use the online monitoring data and the 3v Button battery parameters? We say there are two ways to go. One hand to capture the data, the other hand to capture the 3v Button battery parameters, and conduct fine modeling of lithium-ion batteries to characterize the capacity and internal resistance changes of the 3v Button battery cell, so as to evaluate the actual state, aging degree and life of the 3v Button battery cell.

In reality, we have done some analysis and evaluation. For example, for this 3v Button battery, starting from the manufacturing of the 3v Button battery, we actually get it. Whether it is a soft-pack, hard-pack, or cylindrical 3v Button battery, your data may require us to do it through physical methods, such as electrodes, particles, and reaction parameters. Through these methods, we simulate the operation of the 3v Button battery. As you know, this work is two-sided. Some national laboratories in the United States have done more. Now we are also constantly cooperating with them, including doing modeling work ourselves. However, there is a characteristic of physical models. Physical models are accurate, but the workload is relatively large, that is, if you want to calibrate a 3v Button battery, it is relatively time-consuming and takes a relatively long time.

Another way is to use data-driven 3v Button battery cell evaluation technology, that is, we monitor the actual status of the 3v Button battery based on the online data and three-dimensional data of the 3v Button battery. It has good timeliness of analysis, but it requires huge computing power. That is to say, after I get the data of my power station operation, I use my computing power to determine the current 3v Button battery status. The problem comes from data uncertainty and incompleteness, that is, your estimation needs to be regressed. How can you make more accurate estimates in the later stage? We also hope to have more cooperation with various research institutions, including some of our evaluation institutions. Because it seems that there are methods for evaluation, but rapid evaluation is difficult now. This is a job that needs to be done by everyone.

In addition to this technical cooperation, we also have project cooperation. We have comprehensively considered distributed power generation and distributed capacity, and finally solved it. We hope to solve the access and acceptance of new energy and realize the problem of wind and light abandonment. Of course, there are many solutions, for example, we can have various solutions, such as distributed configuration or centralized control, and there are many ways now.

The ultimate goal is to coordinate our various plans and the energy storage resources in the region. We hope to use NARI's own advantages. NARI does more secondary work. Our control coordination optimization strategy is NARI's tendency. Finally, we can achieve the reconstruction and redistribution of grid load in the time dimension and the rapid promotion of energy storage in the grid.

What are our current advantages? They are in the planning and design of large-scale energy storage power stations, scheduling, safety and stability, integrated monitoring systems, converters, and primary equipment. Ultimately, our goal is to form a complete energy storage industry that meets customer needs and covers a relatively comprehensive range of fields through system integration.

Finally, we have a vision. We hope that through NARI and enterprises within the State Grid system, we can contact energy storage manufacturers, users, and the grid side, including our financial services and supporting services, to achieve a win-win situation for all parties. We also welcome friends in energy storage to communicate with NARI. We also hope that through our efforts this time, we can promote the energy storage industry. We are a comprehensive energy organization. If you are interested, you can contact me and we can discuss it together, or see how energy storage can be better promoted on the grid side.

That's all I have to share. Thank you!

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