Reasonable Control Strategy Research Articles

A Review of Capacity Allocation and Control Strategies for Electric Vehicle Charging Stations with Integrated Photovoltaic and Energy Storage Systems

Electric vehicles (EVs) play a major role in the energy system because they are clean and environmentally friendly and can use excess electricity from renewable sources. In order to meet the growing charging demand for EVs and overcome its negative impact on the power grid, new EV charging stations integrating photovoltaic (PV) and energy storage systems (ESSs) have emerged. However, the output of solar PV systems and the charging demand of EVs are both characterized by uncertainty and dynamics. These may lead to large power fluctuations in the grid and frequent alternation of peak and valley loads, which are not conducive to the stability of the distribution network. The study of reasonable capacity configuration and control strategy issues is conducive to the efficient use of solar energy, fast charging of EVs, stability of the distribution network, and maximization of the economic benefits of the system. In this paper, the concept, advantages, capacity allocation methods and algorithms, and control strategies of the integrated EV charging station with PV and ESSs are reviewed. On the basis of the above research, the current problems and challenges are analyzed, and corresponding solutions and ideas are proposed.

Design Space and Control Strategy for the Manufacturing of Wet Media Milled Drug Nanocrystal Suspensions by Adopting Mechanistic Process Modeling.

Wet media milling is a fully industrialized technology for the manufacturing of drug nanocrystal suspensions. This work describes the development of an advanced control strategy and an associated design space for a manufacturing process at a commercial scale. Full-scale experiments and mechanistic process modeling have been used to establish a physically reasonable control strategy of factors relevant to the quality attributes of the nanocrystal suspension. The design space has been developed based on a mature mechanistic process model of the wet media milling procedure. It presents the process-product attribute relationship between a multidimensional range of measured process parameters and a range of the product-quality attribute mean particle sizes. The control strategy allows for simple, robust, and sound scientific process control as well as the operational flexibility of the suspension batch size. This is an industrial case study of control strategy and design-space definition with the crucial contribution of mechanistic process modeling for an intended commercial manufacturing process.

A field study on the impacts of cold island effect on operating performances of air source heat pump array for space heating

Connecting multiple air source heat pump units in parallel to form an air source heat pump array (ASHP-A) is an important heating approach for central heating in small areas. At a low wind speed, the colder air stream exhausted by outdoor coils of ASHP units cannot effectively mixed with the ambient air and repeatedly return to the outdoor coil for heat exchange, resulting in the local air temperature inside the ASHP-A lower and lower and forming the cold island effect (CIE). CIE may seriously deteriorate the heating efficiency of ASHP units in buildings. However, the impacts of CIE on the operating performances of an ASHP-A were insufficiently studied in existing studies but necessary for developing a reasonable installation standard and efficient control strategy. Therefore, to reveal the impacts of CIE on the operating performances of ASHP units in ASHP-A, the characteristics of CIE, and its impacts on the operating performances of the field ASHP-A were experimentally carried out. The results demonstrated that CIE significantly existed in the field ASHP-A and resulted in frequent defrosting operations and lower heating performances. The defrosting frequency of Unit 1 having a more severe CIE was increased by 243.5 %. The averaged output heating capacity and COP in Unit 1 declined by 27 % and 27.7 %, and these for Unit 2 by 13.6 % and 14.8 %, respectively. The frosting-defrosting loss coefficient for Unit 1 was increased by 519 % relative to Unit 2. This study is valuable to promote the development of installation standards by taking the CIE into consideration for improving heating efficiency of ASHP-A in buildings.

Sensitivity analysis of proton exchange membrane fuel cells based on fixed frequency impedance

Durability is a major constraint to the commercialization of proton exchange membrane fuel cells (PEMFC). An accurate evaluation of the internal state of the fuel cell is necessary to develop a reasonable control strategy. Impedance is one of the important parameters to characterize the internal state of the fuel cell. Making full use of the impedance parameter is of great importance to extend the fuel cell life. The internal sensitivity of the fuel cell is investigated when the reaction parameters are altered. The characteristic frequency is determined to be 2000Hz by the correspondence between the electrochemical impedance spectroscopy and the equivalent circuit model. This frequency is also where the ohmic internal resistance is located. At different current densities, the cooling water temperature and the air stoichiometric ratio are varied. By measuring the variation of the impedance, the change of state inside the stack can be known. The optimal external parameters of the stack reaction can be determined. This study has important implications for making full use of impedance as a characterization parameter and for more rational control of fuel cell systems. Fixed frequency impedance will play an auxiliary role in water and heat management.

Hardware-In-the-Loop test for the optimal damping identification of oscillating buoy wave energy converters

The Power-Take-Off (PTO) damping is a significant factor on energy harvesting capacity of Wave Energy Converters (WEC), which cannot be determined through the traditional laboratory test. In order to consider the complexity of the PTO damping mechanism, the Hardware-In-the-Loop (HIL) methodology is employed to focus on the PTO performance and the energy harvesting capacity in this paper. The dynamic numerical model, servo drives, and data transmission system are integrated in the HIL system, and the established system is then applied to the optimal damping identification of the WEC device which is assembled with the PTO containing a Mechanical Motion Rectifier (MMR). The experimental results indicate that the maximum power appears at the different damping values since the multi-stage energy capture characteristics are affected by the damping mechanism within the mechanical PTO, and the wave height has little effect on the damping values corresponding to the maximum power. This phenomenon is worth noting during the process of the PTO test, and could provide intuitive guidance for the reasonable design and control strategy optimization of the PTO.

Trehalase Inhibitor Validamycin May Have Additional Mechanisms of Toxicology against Rhizoctonia cerealis.

Sharp eyespot is a crucial disease affecting cereal plants, such as bread wheat (Triticum aestivum) and barley (Hordeum vulgare), and is primarily caused by the pathogenic fungus Rhizoctonia cerealis. As disease severity has increased, it has become imperative to find an effective and reasonable control strategy. One such strategy is the use of the trehalose analog, validamycin, which has been shown to have a potent inhibitory effect on several trehalases found in both insects and fungi, and is widely used as a fungicide in agriculture. In this study, we demonstrated that 0.5 μg/mL validamycin on PDA plates had an inhibitory effect on R. cerealis strain R0301, but had no significant impact on Fusarium graminearum strain PH-1. Except for its inhibiting the trehalase activity of pathogenic fungi, little is known about its mechanism of action. Six trehalase genes were identified in the genome of R. cerealis, including one neutral trehalase and five acidic trehalase genes. Enzyme activity assays indicated that treatment with 5 μg/mL validamycin significantly reduces trehalase activity, providing evidence that validamycin treatment does indeed affect trehalase, even though the expression levels of most trehalase genes, except Rc17406, were not obviously affected. Transcriptome analysis revealed that treatment with validamycin downregulated genes involved in metabolic processes, ribosome biogenesis, and pathogenicity in the R. cerealis. KEGG pathway analysis further showed that validamycin affected genes related to the MAPK signaling pathway, with a significant decrease in ribosome synthesis and assembly. In conclusion, our results indicated that validamycin not only inhibits trehalose activity, but also affects the ribosome synthesis and MAPK pathways of R. cerealis, leading to the suppression of fungal growth and pesticidal effects. This study provides novel insights into the mechanism of action of validamycin.

Novel adaptive power distribution master–slave control strategy for a biogas–solar–wind battery islanded microgrid based on a microturbine

As many countries increase their investment in the field of renewable energy, technological research and development has increased on establishing biogas–solar–wind battery islanded microgrids (BSWBIMs) based on biogas generation technology. In BSWBIMs, multiple distributed generators (DGs) are controlled to share either the lack or surplus of power throughout the microgrid. To improve the reliability and economic efficiency of the system, a reasonable control strategy is indispensable. In this paper, a novel adaptive power distribution master–slave (APD–MS) control strategy is proposed to maintain the system voltage and frequency within the Chinese national grid requirements. Moreover, compared with the conventional master-slave control strategy, the proposed control strategy can solve the problem of high dependence on the master DG. Notably, the proposed control strategy can improve the biogas utilization efficiency, system reliability and system stability. The theoretical analysis and software simulation based on BSWBIMs at low voltage levels demonstrate the effectiveness and superiority of the proposed APD–MS control strategy.

Cost assessment of optimal control strategy for brucellosis dynamic model based on economic factors

In recently years, brucellosis between humans and animals in China has shown signs of outbreak again. Brucellosis always takes a heavy toll on human health and profitability of livestock industry, but for farmers, the purpose of breeding is to make profits. Therefore, the optimal control strategy that can maximize the profits of farmers and effectively control brucellosis is needed. It is important to understand the profit mechanism of farmers and disease transmission mechanism in order to design a more effective and reasonable control strategy to maximize the profits of farmers. We propose a dynamic model combining the economic factors, behaviors of livestock farmers and transmission mechanism of brucellosis. Then we investigate the result of the optimal strategy in theory using Pontryagin Maximum Principle and its existence and uniqueness are proved. To verify the accuracy and applicability of the theory, the model are simulated by the least square method based on the price data and infected people data of Ningxia Hui Autonomous Region. The simulation results show that brucellosis is in an outbreak in Ningxia Hui Autonomous Region and the current control policy must be adjusted. Sensitivity analysis indicate economic factors have certain influence on the outbreak of diseases. Under different compositions of three control items (including reduce the contact between susceptible and infected animals, increase the vaccination of susceptible animals, and reduce the discharge of Brucella), we evaluate the optimal control strategy for Ningxia Hui Autonomous Region from profits and infected brucellosis livestock perspectives. The profit results show that the government should increase financial support for disease control and it is effective to implement control by stages.

Research on Magnetic Coupling Flywheel Energy Storage Device for Vehicles

With the increasing pressure on energy and the environment, vehicle brake energy recovery technology is increasingly focused on reducing energy consumption effectively. Based on the magnetization effect of permanent magnets, this paper presents a novel type of magnetic coupling flywheel energy storage device by combining flywheel energy storage with magnetic coupling technology. As a high-efficiency energy storage device, it has the advantages of low energy consumption, low vibration, low noise and easy maintenance. In this paper, firstly, the structural characteristics and working process of vehicle brake energy recovery systems are analyzed, and experiments regarding the transmission and efficiency performance are carried out for key components; then a reasonable control strategy is formulated according to the principle of energy recovery; finally, the speed, acceleration, recovery energy and other parameters are analyzed based on the New European Driving Cycle (NEDC) working conditions. The results show that the energy recovery efficiency reaches 35.59%, which verifies the usability of the device.

Modeling, control and analysis of a novel energy-saving oriented fuel cell anode system

Fuel cell hydrogen supply sub-system needs to provide sufficient mass flow and pressure of hydrogen to meet the working demand of the stack. The hydrogen circulation pump is often used, but causes additional parasitic power of fuel cell system. In this study, a new structure of hydrogen circulation pump is proposed to reduce the parasitic power by using the pressure potential energy of hydrogen flow. The hydrogen feeding system model is established based on the solution of differential equation of state of ideal gas, mass and energy balance. Then, considering the hydrogen intake pressure and the hydrogen excess ratio of the system, a reasonable control strategy is proposed for accurate control. Simulation results show that under the fuel cell work condition and the fuel cell vehicle operation condition, pressure difference between anode and cathode and the hydrogen excess ratio can be regulated to the conditions required by the stack, and the excess ratio error and pressure difference error between anode and cathode is 3.82e-3 and 4.52e-4 Bar, respectively. The parasitic power consumption of the circulating pump is effectively reduced about two-thirds under the fuel cell vehicle operation condition. Then, the effects of anode hydrogen pressure drop, hydrogen inlet pressure and entrainment ratio of ejector on the system are studied. Reducing the anode pressure drop, increasing the ejector entrainment ratio while reducing the hydrogen inlet pressure at low power and increasing it at high power are conducive to energy-saving of the system.

Grouping Control Strategy for Battery Energy Storage Power Stations Considering the Wind and Solar Power Generation Trend

For the optimal power distribution problem of battery energy storage power stations containing multiple energy storage units, a grouping control strategy considering the wind and solar power generation trend is proposed. Firstly, a state of charge (SOC) consistency algorithm based on multi-agent is proposed. The adaptive power distribution among the units started can be realized using this algorithm. Then, considering the trend of wind and solar power generation, a reasonable grouping control strategy is formulated. The grouping situation of the units is determined by using the probability distribution characteristics of energy storage charging and discharging, which reduces the number of charging and discharging conversions and extends the power station life. Finally, the actual data of a wind–solar energy storage microgrid is used to verify the method. The simulation results demonstrate that the proposed method has certain advantages in terms of control effect, SOC consistency, and extending the power station life.

Short Communication: Genetic diversity of walnut blight-associated bacteria from China using rep-PCR

Abstract. Zheng C, Zhu J, Yang X, Fu B. 2022. Short Communication: Genetic diversity of walnut blight-associated bacteria from China using rep-PCR. Biodiversitas 23: 5681-5686. Walnut blight is caused by the bacterium Xanthomonas arboricola pv. juglandis (Xaj), is one of the most serious diseases in walnut production around the world. Understanding the genetic diversity of walnut blight pathogen is of great significance to developing a scientific and reasonable prevention and control strategy. The rep-PCR (Repetitive Sequence Polymerase Chain Reaction) technique is a powerful tool for analyzing plant pathogens. In this paper, using three pairs of rep-PCR universal primers (ERIC, BOX, and REP), a genetic diversity analysis was carried out on walnut blight-associated bacteria mainly isolated from different counties of Hubei Province, China. A study of 60 walnut blight-associated bacteria isolated in 2016 found that they had a high genetic similarity among them. There is no clear correlation between the genetic diversity of these isolates and their geographical or tissue origins. Interestingly, these clusters can also distinguish copper-resistant isolates from sensitive ones. Therefore, rep-PCR is a powerful tool to study the population of walnut pathogenic bacteria.

Can heat pump heat storage system perform better for space heating in China’s primary schools? A field test and simulation analysis

The space heating system has a significant influence on the energy consumption and comfortable indoor environment for primary schools in China’s cold area. This study investigated the operational performance of heat pump systems in two primary schools. Results showed that the primary school buildings had high heating load at turn-on period every morning, which then quickly decreased when the students came to classroom. With this wide-range variation of heating load and unreasonable control strategy, the mismatch between heat source and heating demand happened very easily among the whole heating season. It then led to typical issues and poor energy efficiency of heat pump systems, including excessive space heating after school, low load ratio and frequent start-stop operation of heat pump systems, small water temperature difference and excessive water flow rate of water distribution system, etc. In allusion to those core issues, the heat pump heat storage system (HPHS) was raised for space heating in primary schools to decouple the heat supply side and the heat demand side. Then this study simulated and analyzed the operational performance of HPHS. Results showed that with reasonable control strategy, the excessive heat supply after school was effectively avoided to save almost 51% of the total heat consumption. Besides, the heat pumps could operate stably with almost full heating load for heat storage, thus reaching better energy performance with annual average COP of 5.13. Also the water distribution systems in the ground side, heat storage side and user side could reach better energy performance with high energy efficiency and reasonable water temperature difference among the heating season. Therefore, the HPHSs with reasonable control strategy could effectively solve those typical issues and are more suitable for primary schools.

A comprehensive multi‐hazard risk assessment model for an urban agglomeration with multiple factors

To assist the Department of Emergency Management in understanding the overall risk characteristics and situation of an urban agglomeration for a reasonable risk prevention and control strategy, this study developed a comprehensive multi-hazard risk assessment model for an urban agglomeration with multiple factors. The proposed model includes disaster probability and disaster loss sub-models. The model evaluated four types of disaster risk in urban agglomerations: natural disasters, accidental disasters, public health incidents, and social security incidents. In addition, a variety of factors were integrated into the model, including the socioeconomic foundation of urban agglomerations, the oligopoly effect of core cities, historical disaster losses, the effect of disaster chains, the ability of disaster prevention and mitigation, and intercity coordinated rescue capabilities. Finally, the risk assessment model was applied to the Beijing-Tianjin-Hebei urban agglomeration. The assessment results were compared to the distribution of the new coronavirus pneumonia epidemic in the target urban agglomeration. The results showed that after analyzing the risk characteristics and evaluating the risk levels, the model not only showed the comprehensive risk levels and distribution of urban agglomerations but also revealed the high-risk areas and the key points of risk prevention and control. More importantly, the results obtained through the model can facilitate the strategic planning of disaster prevention and mitigation for urban agglomerations.

Power Tracking Excitation Control and Its Parameter Optimization of Dual-Excited Synchronous Generator

A dual-excited synchronous generator (DESG) with two field windings on the rotor has better dynamic characteristics and high stability. However, the realization of the function needs a reasonable excitation control strategy. In this article, a power tracking excitation control (PTEC) is proposed to improve the operating performances of the DESG. The dynamic processes of a 300-MW DESG with the PTEC are calculated after the disturbance of the torque and reactive power by the time-stepping finite element model, and the results are superior to those adopting the traditional dual-channel excitation control. To further improve the dynamic characteristic of the DESG, the sensitivities of the control parameters of the PTEC to the dynamic characteristic indices are studied. The fuzzy control rules are built based on the sensitivity analysis results and the control parameters are optimized by the fuzzy control method. It revealed the variation laws of the optimized control parameters along with the active and reactive power deviations and their variable rates. The results show that the DESG adopting the optimized control parameters has better dynamic characteristics. The study can provide the theoretic basis for enhancing the system damping effect and suppressing the system oscillation.

Multi-scale dynamics for a lean-burn spark ignition natural gas engine under low load conditions

This work investigates the multi-scale dynamics of the combustion system in a lean-burn spark ignition natural gas engine using different gas injection timings (GIT). The in-cylinder pressure time series are measured, and the indicated mean effective pressure (IMEP) time series are calculated. The influence of GIT on the combustion system is investigated through wavelet analysis, multi-resolution analysis, and the return maps with the GIT covering from 0 to 90°CA after top dead center at the intake stage. Results show that the combustion system has multi-scale chaotic characteristics, and it is sensitive to the change of GIT. The unreasonable GIT will result in serious combustion variations. Meanwhile, the combustion instability of the engine evolves on multiple time scales, showing evident multi-scale oscillation characteristics. All the wavelet power spectrums (WPS) present the characteristics of intermittent short-time periodic oscillations and persistent large-scale periodic oscillations concealed inside the IMEP time series. When the GIT approaches the medium value, the persistence of large-scale periodic oscillations is weakened, while the characteristics of high-frequency intermittent oscillations are enhanced. Under all working conditions, the contribution rate of high-frequency signal D1 decomposed by the IMEP time series to the overall time series fluctuation is about 40% or even higher. The contribution rate of the signal D1 also increases with the aggravation of combustion instability. The return map structures of high-frequency signals D1 and D2 show bifurcation structures, and the bifurcation characteristics of the signal D1 are more evident under medium GIT conditions, indicating a certain correlation between the 2–8 engine cycles, and the correlation between the adjacent engine cycles is stronger. The deterministic relationship between the multiple engine cycles found can help in developing a more reasonable and efficient combustion control strategy, which provides a theoretical basis for improving the stability of a natural gas engine.

Modeling simulation and inverter control strategy research of microgrid in grid-connected and island mode

Under the “double carbon” goal, distributed generation (DG) with inverters will show an explosive growth trend. The microgrid can operate in different modes as a channel for DG to connect to the main grid. In the microgrid, the fast response characteristics of power electronics exacerbate the instability of the microgrid when switching between grid-connected and islanded modes. On the PSCAD/EMTDC simulation platform, a refined power generation model with wind–solar–load–storage microgrid is built to capture the behavior of the system, rather than using a highly simplified model. At the same time, a reasonable control strategy is necessary, which is the key to maintaining the stability of the system. Existing control strategies can only operate in a single mode or the control effect is not ideal. Based on this, on the basis of droop control, the virtual adaptive control loop is added in this study, and the virtual impedance value is adaptively changed according to different output conditions to achieve the purpose of precise control; In the active power control loop, the frequency signal is drawn from the phase-locked loop, and becomes a power feedback variable through the signal transformation process, thereby participating in the power control process and improving the accuracy of frequency control. A standard microgrid power generation model and an inverter control model suitable for grid-connected and off-grid microgrids are built, and the voltage and frequency fluctuations in the two modes are analyzed to verify the effectiveness of the strategy.

Research on Soft Rock Damage Softening Model and Roadway Deformation and Failure Characteristics.

To determine a reasonable control strategy for deep buried soft rock roadways, a study on deformation and failure characteristics was carried out. The Weibull distribution damage variable was introduced to construct a damage-softening model considering the lateral deformation of the rock mass, and the functional relationship between the model parameters F0 and m and the confining pressure were discussed. The nonlinear fitting method was used to correct the model parameters. Using the model, the failure characteristics of deep buried soft rock roadways were analyzed. A comprehensive and step-by-step joint support control strategy was proposed based on the numerical simulation results. The research results showed that the damage-softening model curve established could genuinely reflect the whole process of mudstone failure. The apparent stress concentration phenomenon occurred in the surrounding rock. The surrounding rock deformation showed that roadway floors had larger plastic failure areas than sides and vaults. The plastic failure depth could reach 2.45 m. After a comprehensive and step-by-step joint support control strategy was adopted, the deformation rate of the roadway at the section was less than 0.1 mm/d. The optimized support scheme can effectively improve the stability of the roadway.

Work Efficiency and Economic Efficiency of Actual Driving Test of Proton Exchange Membrane Fuel Cell Forklift.

A 3.5 tonne forklift containing proton exchange membrane fuel cells (PEMFCs) and lithium-ion batteries was manufactured and tested in a real factory. The work efficiency and economic applicability of the PEMFC forklift were compared with that of a lithium-ion battery-powered forklift. The results showed that the back-pressure of air was closely related to the power density of the stack, whose stability could be improved by a reasonable control strategy and membrane electrode assemblies (MEAs) with high consistency. The PEMFC powered forklift displayed 40.6% higher work efficiency than the lithium-ion battery-powered forklift. Its lower use-cost compared to internal engine-powered forklifts, is beneficial to the commercialization of this product.

Prediction of functional zones cooling load for shopping mall using dual attention based LSTM: A case study

Prediction of cooling load for each functional zone is essential for implementing an efficient and economic energy management plan in shopping mall. While previous research has been concerned with the overall cooling load prediction of the shopping mall, which could not provide a reasonable control strategy for the on-demand cooling of functional zone in shopping malls. To address this, we present a novel approach to predict cooling load of functional zones in shopping mall which first uses gray relational analysis methods to screen the key influencing factors of cooling load considering the characteristics of cooling load for different functional zones in shopping mall. It then applies LSTM with dual attention mechanism to optimize the output of the prediction model. Feature attention extracts important features through the analysis of the relationship between historical information and input variables autonomously, while temporal attention improves the prediction accuracy by analyzing the importance of load of each historical moment to the prediction of time load. We evaluate the performance of the proposed approach using real data sets from a shopping mall, which locates at Xi 'an, in the north of China. Experimental results show that cooling load prediction based on function zones may not only better satisfy the cooling load demand of diverse zones, but also ensure that chilled water is available on demand for air conditioning systems. Meanwhile, the short-time zonal cooling load prediction model based on dual-attention-LSTM has increased prediction accuracy, generalization ability, and stability when compared to previous prediction models.