Coordinated Operation Method of Grid Energy Storage and Abandoned Wind

An allocative method of hybrid electrical and thermal energy storage capacity for load shifting based on seasonal difference in district energy planning

The rapid increase in the installed capacity of renewable energy generation has led to the phenomenon of "abandoned solar power" and "abandoned wind power." Some questions, for example, bidirectional power flow, three-phase unbalance, harmonics and voltage crossings can affect the safe operation of the grid. In order to solve the dilemma, the power grid usually uses energy storage devices to store the renewable energy on the spot. In this paper, according to the characteristics of all-vanadium redox flow batteries and regional environmental factors, such as irradiance and ambient temperature, a photovoltaics power generation system model with an energy storage device is established. The problem of capacity allocation in the photovoltaic system is studied. At the same time, the operating cost of the system is evaluated from an economic point of view, and finally the configuration of energy storage and PV capacity with the lowest system operating cost is derived.

Configuring a certain capacity of energy storage for the power system can effectively improve the reliability of the power supply and the level of wind power consumption. This paper takes pumped storage investment cost and wind power consumption demand as the optimization goal, realizes the coordinated operation of pumped storage units and thermal power units, and considers the uncertainty of wind power and load, the multi-timescale characteristics of different types of units and load demand response, and establishes a multi-timescale pumped storage capacity optimization model based on stochastic programming. The model consists of inner and outer layers. The outer layer is investment decision-making, which decides the allocation of pumped storage capacity. The inner layer is for optimization decision-making, and the system optimization operation is carried out in three stages: day-ahead short-term optimization, intraday ultra short-term optimization, and real-time optimization. An example of a typical scenario is established, and the planning results verify the effectiveness of the proposed model and method. The thermal-wind-hydro power system's total cost decreases first and then increases with the increase in the installed capacity of the pumped storage, and the curtailment rate gradually decreases. The total cost increases faster when the pumped-storage installed capacity is larger than optimal. For a pumped-storage power station of the same capacity, variable-speed pumped storage is better than fixed speed pumped storage in reducing the wind curtailment rate. The main reason is that its output is continuously adjustable under the condition of the variable-speed water pump, which is especially suitable for energy storage at night when wind power is high.

Sustainable Nanomaterial-Based technologies for renewable energy production and efficient storage based on Machine learning techniques

The volatility, uncertainty and anti-peaking characteristics of large-scale wind power greatly increase the peak regulation burden of the power grid, which leads to frequently deep peak regulation of thermal power (TP) units. As a result, the total peak regulation cost of the system increases greatly, the operation economy of TP decreases and the phenomenon of abandoned wind gets serious. However, most of the pumped storage (PS) power stations in China adopt the strategy of timing dispatch, which makes its flexibility regulation effect not exerted effectively. Based on the background, the dispatching benefit models of PS and the peak regulation cost model of TP units in the whole process are established respectively. With the objectives of maximizing dispatching benefit of PS, minimizing peak regulation cost of TP and abandoned wind power, a joint optimal dispatching strategy of PS and TP units with large-scale wind power integration is proposed. Based on the 10-unit example system, the peak regulation effect of is simulated and compared between the proposed strategy and the existing operation strategy. The results show that the proposed strategy in this paper can effectively improve the dispatching benefit of PS, the economy of TP peak regulation and the capacity of wind power consumption, which verifies the validity of the proposed strategy.

The anti-peak shaving characteristics of wind power is an important factor that limits the consumption of wind power. The use of the space-time translation capability of a battery energy storage system is one of the effective means for promoting wind power consumption. Thus, this study proposes an energy storage system smoothing wind power fluctuation control strategy considering wind power consumption to improve the utilization level and economy of an energy storage system. First, the statistical characteristics of wind power are analyzed, and the scene division principle of a multiscenario regulation of an energy storage system is formulated using a correlation coefficient. On this basis, the charging and discharging intervals of the energy storage system in each scenario are determined by comprehensively considering the wind power and the time domain distribution law of load. Then, the control strategy of energy storage system based on inter-zone control is proposed based on the division of charging and discharging intervals. During the charging interval, smoothing the upward fluctuation of wind power or reducing the amount of abandoned wind power is aimed at storing electricity. During the discharge interval, electricity is released to smooth the downward fluctuation of wind power. Finally, considering the real-time state of charge and wind power consumption of the energy storage system, a method of charging and discharging power correction based on fuzzy control is proposed. Taking the actual data of a wind farm as an example, a test is performed on a simulation platform of a combined wind storage power generation system to verify the feasibility and superiority of the proposed control strategy.

The World's energy consumption has increased drastically over the past several decades, particularly driven by increasing population and economic activities as well as rising living standards with technological advancements. Since the industrial revolution, fossil fuels have been the major source of energy productions, which is today shown as the primary cause of the ongoing climate change and associated environmental challenges in threatening the existence of many living species and human life and comfort. According to the statistics provided by International Energy Agency (IEA),1 the global energy supply was 14 282 Mtoe in 2018 that is 115% higher than that of the value for 1973. Fossil fuels, such as natural gas, coal and oil are still playing a critical role and covering more than 80% of global energy demands. The concerns associated with global warming and depletion of energy sources have been directing the attention to renewable and environmentally-benign energy solutions. However, efficient, affordable, and nature-friendly energy storage systems are the key to using renewable energy sources effectively. In this study, a comprehensive literature search is conducted to study and bibliografically evalute Canada's energy storage research and development activities over the last five decades. The present study intends to present the cumulative picture on energy storage reseach and development efforts and assess how universities, research institutes and funding agencies have contributed to this particular field. The literature search compiles a total of fifty-year data on energy storage-related research and development activities conducted in Canada. The number of conducted studies associated with energy storage regarding research articles, books, research projects, dissertations, and patents is presented in the period from 1971 to 2021. Furthermore, the Canadian institutes are ranked based on their scholarly ouputs and publications to indicate the most productive ones in the field of energy storage based on the data presented in the literature sources. Energy storage is described as the capture of harvested energy for later use to maintain the balance fluctuations between energy demand and supply. As the world moves towards a low-carbon economy, energy storage systems are exepcted to even play a more critical role in extracting more energy from renewable resources.10 The intermittent characteristic of renewable resources, specifically solar and wind, is one of the major challenges ahead of a reliable and steady renewable energy supply. This can be avoided by storing excess energy to re-use when the renewable resources are not sufficient or unavailable. Energy storage systems can be categorized in different ways in regards to the form of converted and stored energy. Figure 1 presents an overview of energy storage system categories which are considered in this study. It is important to note that chemical energy storage allows to storage and transportation of large amounts of energy for long distances with minimal self-discharge rates, which is crucial for the distribution and effective use of renewable energy resources. Figure 2 presents the energy density of various chemical fuels and batteries. Despite possessing high energy density, environmental concerns associated with the production and consumption of fossil-based chemical fuels, e.g. diesel, gasoline or natural gas, should be adrressed. In regards to nature-friendly chemical energy storage, particularly power-to-gas chemical storage, hydrogen is attracting favorable attention nowadays. In this regard, hydrogen appears to be the lightest and most abundant chemical element in the universe, but is not available freely (by itself). However, it occurs naturally within a compound such as water (H2O); therefore, it is an intermediate energy form. Excess electricity from renewables can be utilized in hydrogen production processes, i.e. electrolysis of water, to store energy in chemical form. Power-to-hydrogen chemical energy storage is a unique and clean method, and it can be compatible with electrochemical storage since hydrogen possesses much greater energy content. One of the major challenges with hydrogen is the low calorific value per unit of volume (MJ/m3) due to its low density. This can be avoided by deploying alternative hydrogen carriers, such as ammonia. Liquefaction at atmospheric conditions, high hydrogen atom content and high energy density characteristics make ammonia a favorable medium for storage and transportation of energy. It is further to note that batteries and capacitors are devices allowing electrochemical storage of electricity. The potential energy is stored in chemical form in batteries, while capacitors are expected to store their potential energy in the form of an electric field.14 Batteries are thus most commonly used and matured options that propose high energy densities and voltages. Lithium-ion (Li-ion), sodium-sulphur (NaS), nickel-cadmium (NiCd), lead acid (Pb-acid), lead-carbon batteries, zebra batteries (Na-NiCl2) and flow batteries are the existing battery types used in various applications. Due to their high specific energy (per unit weight) and high specific energy (per unit volume), lithium batteries attract considerable attention in electrical energy storage. Capacitors can be classified as electrostatic capacitors, electrolytic capacitors, and electrochemical capacitors, among which electrochemical, so-called supercapacitors, promote the highest capacitance per unit of volume owing to a porous structure 15. As a mechanical energy storage method, pumped hydro accounts for more than 95% of the global installed energy storage capacity.15 The main advantage of mechanical energy storage is to readily deliver energy. The method is easy to adapt for conversion and storage of energy from various sourcessuch as water current, wave, or tidal. Pumped hydro, compressed air, and flywheel are the commonly practiced mechanical energy storage methods. Pumped hydro and compressed air are bound to specific geographical characteristics, which is the main restriction for the implementation of these energy storage methods. A flywheel stores the energy obtained from a rotor mass spinning at very high speeds as kinetic energy. The stored kinetic energy can be later used to produce electricity by altering the angular velocity of the flywheel through a decelerating torque and using an electric motor in reverse 16. Despite of being non-suitable for long-term energy storage, flywheels offer favorable advantages, that is, long-life spin, high energy densities and low maintenance costs, and fast charging.17 Thermal energy storage (TES) systems are effective systems to store heat in a reservoir for a period of time (defined or undefined) for later use, that is, space heating and cooling, electricity production, hot water. If the reservoir temperature is kept under the atmospheric temperature, the storage process is called cold thermal energy storage.18 Operating temperature range, capacity requirements, charging and discharging requirements are some of important parameters when choosing an appropriate TES system for a desired application. Since the major proportion of produced and consumed energy is heat around the world, TES systems carries a significant weight regarding the development of effective energy systems . Furthermore, energy losses from the systems commonly occur in the form of heat. Decreasing losses via further utilizing from waste energy is one of many way to mitigate environmental impacts, which can be accomplished by implementing TES systems in a cost effective manner. In the current study, an overview of Canada's energy storage related studies from 1971 to 2021 is presented. The scope of this study is to present the contributions of Canadian universities, research institutes and funders to energy storage research and development efforts over the last five decades. The keywords and methodology that are used for the literature search are depicted in Figure 3. The collected and compiled data for the corresponding fields are presented in figures, and results are discussed in the following sections. In this study, an online literature search is conducted on Canada's energy storage related studies over the last five decades. The current section presents collected and compiled data in charts. The findings of the conducted study are discussed in detail. The most productive institutes of Canada regarding conducting or sponsoring energy storage-related studies are presented. The documents associated with energy storage in all subject areas are presented in Figure 4. In this regard, the highest number of energy storage-related studies were conducted in the subject area of engineering in Canada from 1971 to 2021. The fields of energy and chemistry appear as the other two major subject areas in which high number of energy storage research was conducted. While compiling data, attention has been paid to any potential field conflicts concerning the multi attribution of interdisciplinary publications. Therefore, it should be noticed that chemistry may have an impact on the subject areas of biochemistry, genetics, and molecular biology. The same impact of engineering could be seen on the subject area of energy. The data collected and analysed for comparative evaluation reveals that the Canadian institutes have produced 37 386 energy storage-related academic research publications over the last 50-year period. In this regard, Figure 5A presents the breakdown of energy storage-related publications affiliated to Canada in the corresponding material types in accordance with the publication years. Figure 5A shows that studies in this field consistently increases every year. Consequently, the year 2020 appears as the most productive one in this regard as of April 2021. In the light of this trendline, predicting that the year 2021 will be more productive than 2020 would not be wrong. Figure 5B has been prepared as a heat map to show Canada's provinces where energy storage-related studies were conducted over the last 50 years. In this regard, Ontario appears as the most productive province of Canada in terms of scholarly publications. However, one has to keep in mind that Ontario has the highest number of contributing institutes/universities compared to the rest of the provinces in Canada. Figure 6 presents the breakdown of the number of energy storage-related books, book chapters, and editorials in accordance with publication years in Canada. The year 2018 was the most productive year of Canada by producing 200 documents in the corresponding classification. The other important point that should be pinned in the figure is the year 2005. Compared to the previous year, almost five times more energy storage-related books were published in 2005. Compared to 2019, the number of published books decreased almost by half in 2020. The impact of COVID-19 is recognized as one of numerous reasons behind this result. The number of energy storage-related dissertations completed in Canada over the last five decades is primarily searched through and collected from Library and Archives Canada. The search results are, in this regard, presented in Figure 7. It can be noted that the data presented in Figure 7 is based on the number of energy storage-related theses available in the library; and thus, the results are subject to change in accordance with instantaneous new data entry to the library. As of April 2021, there are 626 energy storage-related MSc and PhD theses/dissertations entered in the online system of Library and Archives Canada. The highest number of theses/dissertations was recorded in the year of 2013 with a value of 62. Based on data collected from the website of Canadian Intellectual Property Office, the number of energy storage-related patents of Canada is 11 719 for the last 50 years. The corresponding results are presented Figure 8. According to this, the year of 2018 appeared to be the Canada's most productive year in terms of patents registered under the title of energy storage. Canada is blessed with institutions that have been supporting energy storage-related research and developments by providing funds. Over the evaluated period of 50 years, the Natural Sciences and Engineering Research Council of Canada (NSERC) appears as the major funding agency for Canada's energy storage related research, development, partnership, strategic innovation and commercialization efforts and has supported more than 8500 projects in the field of energy storage. A total number of projects that have been funded by Canadian institutes have become 18021 from 1971 to 2021. It is most likely to observe a major increase in the number of projects by the impact of the recent hydrogen strategic plan of Canada. Being an excellent energy storage medium is one of many advantages of hydrogen. Therefore, there is a significant correlation in between hydrogen and energy storage research efforts. The subject matter report is already named as call-to-action for green hydrogen transition for the energy sector. In the report, the importance of dedicating more domestic resources to green hydrogen efforts to achieve the targets by 2050 is emphasized clearly (Figure 9). The development and implementation efforts of effective, affordable, and nature-friendly energy storage systems are recognized as a key requirement in achieving a green energy transition. In this regard, Canada intends to be the country leading and inspiring many others. Figure 10 shows the a number of Canadian institutes/universities that have produced more than 100 scholarly publications on energy storage under the subject area of energy. According to this, the total number of such scholarly publications has been 9125 over the past five decades. The results clearly show that there are two universities, such as University of Waterloo with 809 publications and Ontario Tech. University (formerly University of Ontario Institute of Technology) with 697 publications, leading in this particular area. University of Waterloo appears as the most productive Canadian university with a total number of 809 publications while Ontario Tech. University, which is one of the Canada's youngest universities, follows with a total number of 697 publications. The specific affiliations in the publications show that the researchers working in the productive environment of Clean Energy Research Laboratory (CERL) at Ontario Tech. have played a major role in this achievement. The data that support the findings of this study are available in Scopus, Library and Archives Canada and Canadian Intellectual Property Office with the reference number of [17], [18], and [19], respectively. These data were derived from the following resources available in the public domain: https://www.scopus.com/search/form.uri?display=basic&zone=header&origin, https://www.bac-lac.gc.ca/eng/services/theses/Pages/search.aspx, https://www.ic.gc.ca/opic-cipo/cpd/eng/search/basic.html?wt_src=cipo-patent-main.

On the marginal value of electricity storage

Optimal allocation of energy storage capacity for hydro-wind-solar multi-energy renewable energy system with nested multiple time scales

The fast and flexible regulation characteristics of energy storage system make it have advantages in participating in system frequency control. Combining wind power and energy storage to form a coordinated wind-storage system can well improve the frequency stability of the system. However, considering the high energy storage investment cost, this paper establishes the energy storage capacity optimization model with the goal of minimizing the total cost of coordinated wind-storage system. Then, a fuzzy control strategy of dynamic frequency response of the coordinated wind-storage system is proposed, which makes full use of the active reserve margin of wind turbine and the limited capacity of energy storage equipment to realize the dynamic cooperative operation of wind power and energy storage. Finally, the simulation analysis of the proposed method verifies that the optimization of energy storage capacity has good economy and the control strategy has good frequency regulation control effect.

Numerous problems have emerged with the rapid development of wind power in Xinjiang. The predominant problem is the inhibition of the healthy development of the wind power industry by wind power curtailment in Xinjiang. In this study, wind power heating and high energy-consuming industries were coupled to increase wind power consumption in Xinjiang on the load side. The feasibility analysis of wind power heating in Dabancheng showed that the heating load characteristics coincide with the wind characteristics and the electric heating technology can fulfill the requirements for wind power heating. A business model innovation achieved a win–win situation. Furthermore, a wind power heating system was designed in Dabancheng, the boiler capacity and the heat storage capacity were calculated, and a heating system model with heat storage technology was established. Wind power heating with heat storage can improve the consumption of wind power and increase the local electric load and system adjustability. Furthermore, heating with curtailed wind power can save 2942 tons of standard coal as well as reduce 5172 tons of CO2, 2.9 tons of SO2, 22 tons of NOX, and 2 tons of soot emissions. Non-grid-connected distributed wind power was applied to the high energy-consuming coal chemical industry to reduce wind power curtailment, expand the consumption market, and reduce pollution. A multifunctional wind-photovoltaic complementary system with hydrogen energy storage coupled with traditional high energy-consuming coal chemical industry was established. The implementation plan using wind and solar energy to produce, store, and apply hydrogen energy was proven beneficial. Wind power consumption was improved on the load side. The wind power curtailment problem was reduced by increasing local load using the curtailed wind power to provide clean heat in Dabancheng and constructing the multifunctional wind–photovoltaic complementary system. This study will contribute to the healthy and sustainable development of the wind power industry in Xinjiang.

Energy storage in wind farms can stabilize the fluctuation of wind power output. Shared energy storage can reduce the construction cost of energy storage devices and stimulate the enthusiasm of wind farms to invest in energy storage. The wind power base is composed of multiple wind farm groups. Existing research methods did not consider how to allocate shared energy storage among wind farm groups in the wind power base. This paper proposes an energy storage capacity allocation method for wind farm groups. Firstly, a bilevel model for the shared energy storage allocation is established. The upper-level model optimizes the shared energy storage allocation of each wind farm group with the goal of minimizing the over-limit power export risk in the wind power base; The lower-level model calculates the over-limit power export of each wind farm group according to the energy storage capacity allocation and transfers the value of over-limit power export to the upper-level model. The bilevel model can be converted to a two-stage model that can be solved sequentially; The wind power base in Belgium is used for numerical simulation to verify the effectiveness of the proposed model. Finally, the sensitivity of confidence level, total energy storage capacity, and risk preference factor are analyzed.

Battery energy storage is used for dispatching the fluctuations of wind power, but it has a slow response and limited life cycle. Therefore, capacitor energy storage is interconnected with battery energy storage to make a hybrid energy storage system for absorbing the high frequency part of the wind power output. The wavelet decomposition method is applied to decompose the wind power into high and low frequency parts. The capacitor absorbs the high frequency part, and two batteries absorb the low frequency part. In the low frequency region, the power allocation is conducted to batteries that have different capacities, but the same lifecycle characteristics. The simulation is examined with MATLAB, and the result shows that the proposed method has good smoothing performance and can prolong the battery life.

Thermo-economic assessment of sub-ambient temperature pumped-thermal electricity storage integrated with external heat sources

An adaptive short-term prediction scheme for wind energy storage management