Coordinated Control Strategy Research Articles

The impacts of socioeconomic development and climate change on long-term nutrient dynamics: A case study in Poyang Lake

The anthropogenic activities associated with rapid socioeconomic development affect global climate change and the water quality of lake ecosystems. However, the impacts of socioeconomic and climate changes on lake nutrient dynamics require additional study. In this study, we used a long-term dataset (1987–2021) of Poyang Lake to identify the nutrient dynamics and assess the impacts of social and climatic factors on nutrient concentrations. The filtering trajectory method (FTM) suggested that in Poyang Lake, nutrients first increased and then decreased, with TP reaching its highest value of 157 μg/L in 2015. The study employs a combination of structural equation modeling (SEM) and FTM to identify the complex interactions between socio-economic and climatic factors affecting nutrient concentrations in Poyang Lake. The SEM results revealed that socioeconomic factors rather than climate change determined the long-term changes in TN and TP. Additionally, FTM results verified that GDP, urbanization (Ur) and P-fertilizer (Pfer) were the key drivers of TN; Ur, population (P), and sewerage treatment rate (STR) were the primary factors of TP. Through generalized additive models (GAMs), we observed that GDP accounted for 86 % of the temporal variability in TN and 45.7 % of that in TP, exhibiting inverted U-shaped relationships with both TN and TP. Air temperature (AT), a climatic factor accounted for only 44.6 % and 14.8 % of the variation in TN and TP, respectively. In addition, Pfer explained 66.0 % of the variation in TN, and STR explained 50.4 % of the variation in TP with a peak TP at the STR threshold of approximately 80 %. Our findings highlight the importance of Pfer and STR as critical indicators for watershed nutrient management. The identification of key temporal drivers and nutrient trajectories provides a scientific basis for developing management strategies. The results highlight coordinated control strategies for water pollution and carbon reduction as essential measures for mitigating climate change.

Improved differential protection for two-terminal weak feed AC system considering negative sequence control coordination strategy

The flexible DC transmission project of renewable energy has become an inevitable development trend for large-scale renewable energy grid connection. Its two-terminal weak feed AC system is often composed of 100 % power electronic power equipment. The fault control strategy is used at both ends of the line to change the fault current characteristics, leading to a decrease in the performance of traditional differential protection. Based on analyzing the adaptability of current differential protection in the two-terminal weak feed AC system under traditional control strategy (TCS), this paper proposed an improved differential protection for two-terminal weak feed AC system considering negative sequence control coordination strategy. Firstly, the fault characteristics of the two terminal weak feed AC systems are analyzed. On this basis, the adaptability of differential protection under TCS is analyzed, and the quantization function that can quantify the operation performance of differential protection is given. Secondly, based on the problem of the traditional negative sequence control strategy, an improved control strategy is introduced and the operation performance of differential protection under the improved control strategy is studied. Finally, an improved differential protection scheme based on the change of current amplitude is proposed. Simulation results show that the proposed protection scheme can resist higher fault impedance(300 Ω) and noise interference(25 dB). In addition, the proposed differential protection scheme is suitable for the protection requirements of the two terminal weak feed AC systems in different scenarios and has higher sensitivity.

Coordinated control strategy for improving frequency security of LCC[sbnd]HVDC sending-end system with large-scale wind power

To improve the frequency security of the LCCHVDC sending-end system with high penetration of wind power system and achieve optimal utilization of frequency regulation resources, a cooperative control strategy involving wind power and LCCHVDC in frequency regulation is proposed. Firstly, under a variety of scenarios, the power support requirements of LCCHVDC sending-end system are analyzed according to the power regulation margin of various frequency regulation resources and the disturbance power, and a multi-time scale frequency regulation control strategy for DFIG based wind farms is proposed, which combines the advantages of variable speed control and variable pitch angel control. And a cooperative control strategy of DFIG and LCCHVDC considering the frequency regulation deadband is proposed. Then, based on the maximum power regulation margin of synchronous generators and wind farms, the key control parameters of relative control links are designed to enable them autonomously adjust the active power according to various scenarios to involve in inertia response and primary frequency regulation task. Finally, the effectiveness of the control strategy is verified by the simulation model of LCCHVDC sending-end system with large-scale wind power, which significantly improves the frequency security and stability.

Analysis of the Influencing Mechanism of Space-time Heterogeneity of Greenhouse Gas Emissions from Agriculture in China

Agricultural greenhouse gas emission reduction plays an important role in addressing global climate warming. Researching and revealing the spatial and temporal characteristics, as well as the influencing mechanisms of agricultural greenhouse gas emissions, is of great significance for achieving the goals of green and low-carbon development in agriculture. This study examines the agricultural greenhouse gas emissions from 31 provinces （municipalities, autonomous regions） in China from 2000 to 2020. Through the use of geographic detectors, spatial econometric analysis, and other methods, it explores the spatiotemporal evolution characteristics and driving factors of agricultural greenhouse gas emissions. The results indicated the following： ① From 2000 to 2020, agricultural greenhouse gas emissions in China showed a development process of "slow increase - sharp increase - sharp decrease." ② The spatial heterogeneity of agricultural greenhouse gas emissions was significant, forming three high emission areas in space： the central high emission area centered on Henan, the southern high emission area centered on Guangdong, and the southwestern high emission area centered on Sichuan. The center of gravity showed a trend of shifting northward and westward. ③ Rural population, regional gross domestic product, and agricultural output value were the dominant driving factors causing spatial heterogeneity of agricultural greenhouse gas emissions. ④ Agricultural greenhouse gas emissions had spatial spillover effects. When formulating agricultural greenhouse gas reduction targets, it is necessary to adopt a coordinated control strategy among different regions.

Flexible heat and power load control of subcritical heating units based on energy demand-supply balance

To fulfill the requirement for enhancing the flexibility of heating units within the framework of renewable energy grid integration. In this study, a proposed optimal control strategy for heating units borrows the heat extraction output to perform rapid load changes; the boiler heat supply within the unit is clearly differentiated from the turbine energy demand, and formulate corresponding control signals. The coordinated control of the boiler and turbine based on the energy demand-supply balance of the unit as secondary control for the final load accuracy, ensuring its safe and stable operation. To further enhance the control performance, an improved sparrow optimization algorithm with butterfly search is designed to adjust the controller parameters. Finally, field tests on a 300MW subcritical heating unit reveal that the automatic generation control performance index is improved by 32.16% compared to the traditional coordinated control strategy, while taking less impact on the heat user. These results validate the exceptional performance and significant practical value of the optimized control strategy.

Path tracking and energy efficiency coordination control strategy for skid-steering unmanned ground vehicle

The skid steering unmanned ground vehicle (SUGV) plays an important role in extremely harsh environments. Improving the autonomous control capability and energy efficiency of SUGV is urgently needed. This article presents a skid steering-based path tracking control strategy. In the upper controller, an improved model-free sliding mode controller (APMS) is used to calculate the yaw moment for tracking control. On the lower controller, the Snow Ablation Optimizer (SAO) is used to distribute the output torque of the drive motors, taking longitudinal force, yaw moment and energy consumption into account. Finally, the designed controller is validated through simulation under different operating conditions. The results show that the proposed coordination controller achieves good control performance, increases energy efficiency and at the same time ensures tracking accuracy.

Interactive effects of outdoor fine particulate matter and metabolic, behavioural, and psychosocial risk factors on cardiovascular disease: analysis of the PURE-China cohort study

Abstract Background Long-term PM2.5 exposure has been associated with an elevated risk of cardiovascular disease (CVD) and its associated risk factors.[1–4] There is a paucity of studies investigating the interactive effects of PM2.5 exposure and a comprehensive list of risk factors including metabolic, behavioural, and psychosocial risk factors on CVD risk.[5] Purpose This study aims to examine the interactive effects of PM2.5 exposure and metabolic, behavioural, and psychosocial risk factors on incident CVD. Methods The Prospective Urban Rural Epidemiology (PURE)-China cohort study is a population-based cohort study recruiting participants aged 35–70 years from 115 communities in 12 provinces of China between 2005 and 2009, and followed up until August 31, 2021.[6] Participants’ metabolic, behavioural, and psychosocial risk factor information was recorded. PM2.5 concentrations were extracted from a 1x1 km2 global model.[7,8] For this analysis, we included participants aged 35–70 years at baseline without a history of CVD, with at least one follow-up visit. The primary outcome was a composite of major cardiovascular events (CVD deaths, myocardial infarction, stroke, and heart failure). Additive interaction was measured by relative excess risk due to interaction (RERI), the proportion of disease attributable to interaction (AP), and the synergy index (SI).[9,10] To comply with the additive interaction method, we classified concentrations of PM2.5 into low and high levels by the median of 3-year average PM2.5 concentration (45.7 μg/m3, IQR: 33.7-74). Cox proportional hazard models were used to assess the associations of metabolic, behavioural, and psychosocial risk factors on incident CVD by PM2.5 concentrations. Results The PURE-China study recruited 47 931 participants, of which 39 329 are eligible for this analysis. During the median follow-up period of 11.9 years (IQR: 9.6-12.6), 1462 and 2155 major CVD events had occurred in the low and high PM2.5 group respectively. There was a synergistic interaction between PM2.5 and the systolic blood pressure (SBP) for CVD: RERI: 0.363, 95% CI: 0.196-0.531; AP: 0.098, 95% CI: 0.081-0.115; SI: 1.155, 95% CI: 1.132-1.177; high LDL cholesterol: RERI: 0.219, 0.003-0.436; AP: 0.135, 0.008-0.263; SI: 1.549, 0.947-2.533. A significant synergistic interaction was also identified between PM2.5 and household air pollution (RERI: 0.457, 0.292-0.622; AP: 0.277, 0.184-0.37; SI: 3.362, 1.409-8.019). Interactions between PM2.5 and low grip strength on CVD were significantly synergistic, but antagonistic between PM2.5 and low physical activity (RERI: -0.248, -0.485--0.012; AP: -0.174, -0.349-0.001; SI: 0.633, 0.412-0.971). Conclusion Addictive interaction was between PM2.5 and SBP, high LDL cholesterol, household air pollution, low grip strength and low physical activity on incident CVD, indicating the benefit of coordinated control strategies for metabolic, physical, and environmental risk factors for the prevention of CVD.

A Fuzzy Adaptive PID Coordination Control Strategy Based on Particle Swarm Optimization for Auxiliary Power Unit

Range extender hybrid vehicles have the advantages of better dynamics and longer driving range while reducing pollution and fuel consumption. This work focuses on the control strategy of an Auxiliary Power Unit (APU) operating in power generation mode for a range-extender mixer truck. When an operating point is switched, the engine speed and generator torque of the APU will switch accordingly. In order to ensure APU fast and stable adjustment to meet the power demand of the vehicle as well as operate at the lowest fuel consumption, a fuzzy adaptive PID coordination control strategy based on particle swarm optimization (PSO) is proposed to control the APU. The optimal operating curve of APU is calculated by coupling the engine and generator first. Then, the adaptive PID algorithm is used to control the speed and torque of the APU in a dual closed loop. The PSO is used to optimize the PID control parameter. Through hardware-in-the-loop tests under different working conditions, the control strategy is verified to be effective and real-time. The results show that the proposed control strategy can coordinate the operating of engine and generator and control the APU to track target power stably and quickly under minimum fuel consumption. Compared with traditional PID control strategy, the overshoot, regulation time and steady-state error are reduced by 55.1%, 11.1% and 77.3%, respectively.

A variable droop coefficient-based reactive power coordinated control strategy in wind farm

A variable droop coefficient-based reactive power coordinated control strategy in wind farm

Stability coordinated control strategy of autonomous unmanned 4WID-4WIS vehicle based on APD-LQR and AFSMC

To improve the four-wheel independent driving and four-wheel independent steering (4WID-4WIS) autonomous unmanned vehicles’ active safety performance at their maximum operating capacity, the control of path following, four-wheel steering (4WS) and lateral stability should be coordinated. This paper introduces a hierarchical coordinated control framework, in which several independent controllers collaborate to enhance the overall performance of the vehicle system. Initially, in the upper controller, an adaptive preview distance linear quadratic regulator (APD-LQR) path following algorithm is proposed, considering the dynamic characteristics of the tire. It aimed at making the following error converge and obtaining the optimal front wheel steering angle. Meanwhile, an adaptive fuzzy sliding mode control (AFSMC) algorithm is implemented for obtaining additional yaw moment. It aimed at coordinating and improving effectively path following performance and lateral stability. Using the phase plane approach, the sliding surface is dynamically modified. Subsequently, in the lower controller, a rear wheel angle controller based on vehicle speed is proposed. It aimed at further enhancing vehicle’s maneuverability and stability by fully utilizing its steering redundancy features. Moreover, a torque distribution controller establishes a comprehensive cost function and then the NSGA-III algorithm is employed to optimize the torque distribution coefficients. Finally, simulation and Hardware-in-Loop (HIL) test results demonstrates that the proposed coordination algorithm can fully utilize the redundancy features of the 4WID-4WIS vehicle, and significantly enhances the vehicle’s path following accuracy and lateral stability, especially under extreme driving conditions.

Research on coordinated control strategy of distributed static synchronous series compensator based on multi-objective optimization immune algorithm

Research on coordinated control strategy of distributed static synchronous series compensator based on multi-objective optimization immune algorithm

Coordinated strategy for path tracking and dynamic stability considering extreme obstacle avoidance in distributed drive electric vehicles

PurposeThis research aims to investigate the trajectory tracking problem for a four-wheel independent drive autonomous vehicle (4WID) and propose an integrated, coordinated control strategy to address the mutual interference between trajectory tracking and stability control in extreme cases.Design/methodology/approachThe authors establish an adaptive preview model that modifies the preview distance based on vehicle speed. They utilize a three-degrees-of-freedom vehicle model and employ model predictive control to calculate the necessary front wheel angle for trajectory tracking. In terms of longitudinal control, a longitudinal coordinated control mechanism is established to achieve the two conflicting objectives of trajectory tracking accuracy and dynamic stability through early deceleration. A stability controller based on sliding mode control (SMC) is designed, considering tire constraints and tracking the optimal yaw angle and sideslip angle. Furthermore, a lateral coordinated control strategy is developed, considering the weight coefficient of stability control, and the yaw moment is calculated and distributed based on the vehicle torque requirements.FindingsThe proposed integrated, coordinated control strategy successfully addresses the mutual interference between trajectory tracking and stability control in extreme cases for the 4WID vehicle. The strategy achieves trajectory tracking accuracy, dynamic stability and reduced energy consumption while taking into account tire constraints.Originality/valueWe have proposed a cooperative control strategy for the trajectory tracking problem of autonomous driving vehicles. This strategy is different from previous methods in that we have taken into account the integrated dynamic control in both longitudinal and lateral directions, balancing the conflicting control requirements and reducing energy consumption, improving trajectory tracking accuracy and vehicle dynamic stability. We have verified the feasibility of this strategy through joint simulation under different driving conditions.

Efficient power management strategies for AC/DC microgrids with multiple voltage buses for sustainable renewable energy integration

This study proposes a distinct coordination control and power management approach for hybrid residential microgrids (MGs). The method enhances the feasibility of hybrid MGs by reducing power loss on ILBCs. The MG has been modeled with solar and wind generators. The MG comprises multiple direct current (DC) and alternating current (AC) sub-microgrids (SMGs) with varying voltage levels. The coordination control and power management strategies for autonomous hybrid MGs with primary and secondary control levels. A novel technique is proposed to ensure seamless and precise power transfer among SMGs while minimizing the constant operation of ILBCs in islanded mode, with a focus on the secondary control level. The study uses MATLAB/Simulink to analyze on-grid, off-grid, and transient mode power transfer among MG. The MG has been operative during transient/faulty conditions. The results indicate that the proposed method demonstrates excellent adaptability in managing power flow.

Research on a coordinated control strategy of three-phase photovoltaic converters based on a buck–boost DC link

Research on a coordinated control strategy of three-phase photovoltaic converters based on a buck–boost DC link

Coordinated frequency control strategy for modern power system considering engagement willingness

The large scale integration of renewable energy sources (RES) is posing unprecedented challenges to the frequency stability of modern power systems, with system inertia being the primary concern. Under such a landscape, this paper introduces a coordinated control strategy aiming at enhancing frequency stability by swiftly adjusting the power output of flexible resources to mitigate power imbalances and further dampen frequency fluctuations. Firstly, a communication-free center of inertia (COI) frequency estimation method is proposed. An equivalent inertia estimation method tailored for modern power systems is then developed by exploiting the correlation between synchronous inertia and active power fluctuations. By integrating the COI frequency variation rate with the estimated equivalent inertia, the imbalance power is calculated and compensated through the proposed coordinated control strategy. In this work, two typical flexible resources including photovoltaic (PV) generation and electric vehicles (EVs) are modeled and integrated into the testing system in PSCAD/EMTDC. Considering the contradiction between maximizing generation profit and reducing power output to mitigate frequency variation, the Corporate Social Responsibility (CSR) of renewable Generation Companies (GENCOs) is modeled to sketch their willingness of engaging into frequency support. Moreover, the frequency modulation potential of EVs in both commercial and residential areas are quantified for practical implementation. The simulations results successfully validate the effectiveness of the proposed control strategy.

Coordinated Control of Transient Voltage Support in Doubly Fed Induction Generators

The large-scale integration of wind power significantly alters the voltage dynamic characteristics of power systems. Wind turbines have a weak ability to withstand grid disturbances and have difficulty in providing effective reactive power support during transient periods. The sensitivity of wind turbines to the grid voltage significantly increases the probability of large-scale, cascading off-grid events. This paper proposes a coordinated control strategy to enhance the transient reactive power support capability of doubly fed wind farms. The additional stator current demagnetization control reduces the risk of a crowbar protection action after a fault and ensures that the unit power is controllable. Based on the voltage–reactive power coupling relationship, each unit can produce reactive power according to the voltage–reactive power sensitivity matrix during the transient period. After the reactive power output of the unit reaches the limit, transient active and reactive combined control is further adopted to reduce the active power output of the unit to a certain extent and improve the reactive power support capability. Finally, two cases are built in the PSCAD to verify the effectiveness of the proposed control strategy. The results show that the proposed control strategy can enable the wind farm to output more reactive power to the grid during the transient period, effectively supporting the system voltage during the transient process and avoiding further deterioration of the fault.

Coordinated control algorithm of hydrogen production-battery based hybrid energy storage system for suppressing fluctuation of PV power

Photovoltaic (PV) power generation has issues of volatility and intermittency. Currently, PV plants are generally equipped with 10% rated capacity lithium-ion (Li) battery energy storage systems in China, who often fail to suppress fluctuation in the output power of PV plants effectively and meet the grid-connected standard. The hybrid energy storage system (HESS) combining with hydrogen production and Li battery system can produce hydrogen by water electrolysis during the peak period of PV power generation, effectively improving PV utilization efficiency, while smoothing PV power fluctuation and improving grid connection electricity quality. Firstly, models of the solid oxide electrolysis cell (SOEC) and alkaline electrolysis cell (AEC) systems for hydrogen production, and Li battery energy storage system are established, and the transient response characteristics of each system are analyzed. Secondly, an adaptive wavelet packet decomposition (AWPD) method for PV power signal decomposition is proposed based on the wavelet packet decomposition (WPD) method. Thirdly, a capacity configuration method for HESS are proposed based on the APWD method. Fourthly, a coordinated control strategy for HESS is proposed with the transient response characteristics of different energy storage systems and the state of charge for Li battery system. Finally, the proposed method is validated through simulation experiments based on the actual power data of the PV plant. The results show that the developed methods can effectively utilize partial PV power generation to produce hydrogen, improve PV utilization, and the combined output power of PV plant and HESS can fulfill the grid-connected standard.

A Coordinated Control Strategy for Efficiency Improvement of Multistack Fuel Cell Systems in Electric–Hydrogen Hybrid Energy Storage System

A two-layer coordinated control strategy is proposed to solve the power allocation problem faced by electric–hydrogen hybrid energy storage systems (HESSs) when compensating for the fluctuating power of the DC microgrid. The upper-layer control strategy is the system-level control. Considering the energy storage margin of each energy storage system, fuzzy logic control (FLC) is used to make the initial power allocation between the battery energy storage system (BESS) and the multistack fuel cell system (MFCS). The lower-layer control strategy is the device-level control. Considering the individual differences and energy-storage margin differences of the single-stack fuel cell (FC) in an MFCS, FLC is used to make the initial power allocation of the FC. To improve the hydrogen-to-electricity conversion efficiency of the MFCS, a strategy for optimization by perturbation (OP) is used to adjust the power allocation of the FC. The output difference of the MFCS before and after the adjustment is compensated for by the BESS. The simulation and experiment results show that the mentioned coordinated control strategy can enable the HESS to achieve adaptive power allocation based on the energy storage margin and obtain an improvement in the hydrogen-to-electricity conversion efficiency of the MFCS.

Learning-based hierarchical cooperative eco-driving with traffic flow prediction for hybrid electric vehicles

The integration of autonomous driving and hybrid electric vehicle technologies presents a promising solution for achieving environmental sustainability. This paper introduces an innovative energy-efficient driving strategy for hybrid electric vehicles that incorporates real-time traffic flow prediction. The study delves into the impact of both lateral and longitudinal vehicle maneuvers on energy consumption within dynamic traffic environments, offering novel insights into optimizing energy utilization. Firstly, a multi-lane traffic flow state rolling predictor is constructed based on the Hankel dynamic mode decomposition algorithm. Subsequently, a vehicle longitudinal and lateral coordinated control strategy is established by integrating the prioritized experience replay double deep Q-network algorithm. Finally, a novel energy management strategy is proposed that leverages Simulink dynamic model and the deep deterministic policy gradient algorithm to address the vehicle dynamic decision-making planning results. Within a hierarchical cooperative optimization framework, this research comprehensively considers safety, comfort, traffic efficiency, and fuel economy. By introducing a novel hierarchical collaborative ecological driving framework, we have achieved a substantial improvement in environmental sustainability, with traffic efficiency increasing by 10.27%-14.41% and fuel economy rising by 9.44%-10.47%. Hardware-in-the-loop validation has confirmed the proposed approach’s real-time capabilities and promising practical applications.

Frequency Support Coordinated Control Strategy of Renewable Distributed Energy Resource Based on Digital Twins

The integration of high-penetration renewable energy sources is playing an increasingly important role in the frequency regulation of the power system. However, due to the varying output characteristics and response speeds of different renewable distributed energy resources (DERs), the overall response from the collective output of these distributed energy resources may not meet expected requirements and could have adverse effects on the grid. One drawback of traditional distributed coordinated control is its high communication requirements. This paper proposes using digital twin (DT) technology for the coordinated control of distributed energy resources, which can minimize the communication needs between various distributed energy resources while achieving coordinated control. Verification of the frequency support coordinated control strategy based on digital twin technology shows that it can effectively enhance the individual output characteristics and overall response of each distributed energy resource, providing effective support for grid frequency.