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With the increasing penetration of wind power into the grid, its intermittent and fluctuating characteristics pose a challenge to the frequency stability of grids. Energy storage systems (ESSs) are beginning to be used to assist wind farms (WFs) in providing frequency support due to their reliability and fast response performance. However, the current schemes mostly focused on the sole operation of either WT or ESSs for frequency support, lacking in economy and reliability. To address these issues, this work proposes a sliding mode consensus control (SMCC) method for ESSs to assist the frequency response of WTs. First, a coordination strategy for the WTs and ESS is proposed to reinforce the frequency support capability of a WT–ESS by determining the optimal capacity of ESSs. Meanwhile, a novel SMCC is proposed to achieve proportional power sharing among ESSs and increase the total power output of the entire WFs during wind energy shortages. Moreover, an event triggered communication mechanism is utilized to reduce the information exchanges among ESSs. Subsequently, a Lyapunov stability analysis is conducted to prove the stability and finite time consensus of the proposed method. Simulation case studies are conducted in IEEE 39-bus system to validate the effectiveness of the proposed framework. [ABSTRACT FROM AUTHOR]

Energy storage systems (ESSs) are being utilized to improve wind farms’ (WF) frequency support capability due to their high reliability, fast response and the dual role of energy users and suppliers. Nevertheless, the problem of how much capacity should each ESS possesses in order to better serve the WFs has never been investigated. With this perspective, this paper proposes an optimal ESS allocation (OEA) scheme for doubly fed induction generator (DFIG) based WFs to mitigate the impact of wake effect in frequency support. Firstly, the synchronous stability of wind turbines under frequency dips is analyzed with the concept of frequency support margin (FSM), and the detrimental impact of the wake effect is also investigated. Subsequently, the role of ESSs to improve wind turbines’ synchronous stability is demonstrated. To make the OEA scheme practical, the wind turbines in a WF are segmented into different clusters based on the received wind speed. Afterwards, the OEA problem is formulated, where the objective is to optimize the coherency of the wind turbine clusters’ FSM level. The simulation results show that ESS can provide secondary frequency support under major grid frequency drops, and the proposed OEA scheme can reduce the risk of loss of synchronous stability. [ABSTRACT FROM AUTHOR]

• A novel coordination scheme for Wind, PV and battery energy storage systems; • A multiple objective control framework which transforms the control objectives into BESS's set points; • A containment control approach for distributed control of BESS to allow the co-achievement of four objectives; • Finite time convergence of the distributed control is achieved to allow parametric prescription of the convergence time. This paper proposes a finite time containment control scheme to achieve distributed control of a weak grid which is integrated with photovoltaic (PV), wind turbine (WT) and battery energy storage system (BESS). Taking advantage of the containment control in multi-dimensional control, we proposed a multi-objective control scheme of the WT-PV-BESS system in a weak grid, wherein four control objectives are specified, namely, bus voltage regulation, grid frequency control, peak load shaving and economic benefits optimization for the system operator. Firstly, the sizing approach of BESSs to fulfill the operation mission requirements is proposed; meanwhile, the general coordination strategy for the PV, WT and BESS to achieve the demand–supply balance is proposed. Subsequently, the predefined four control objectives are modeled and transferred into the long/short time frame operational constraints of the BESSs. Afterwards, the finite time containment control algorithm is proposed to force the BESSs into achieving containment status within prescribed time. Simulation case studies are conducted on a modified IEEE 9-bus system to show the effectiveness and performance of the proposed scheme. [ABSTRACT FROM AUTHOR]

This paper proposes a fractional-order sliding mode controller (FOSMC) for fixed-time stability of multimachine power systems. Fractional calculus has been applied in sliding mode control (SMC) to design FOSMC which can better suppress the chattering phenomenon than the traditional integer-order SMC. Hence, a FOSMC is proposed to regulate the excitation of synchronous generators to improve the transient stability of the power system. In addition, the FOSMC can maintain the multimachine power systems stabilization in an upper bound and measurable convergence time independent of the initial operating conditions of the power system. The Lyapunov function is implemented to demonstrate the stability of multimachine power systems under the FOSMC, and the upper bound convergence time of the power system is generally estimated. The New England 10-machine 39-bus power system is taken into simulation to test the effectiveness and superior performances of the FOSMC than the existing control methods under different operating conditions. Meanwhile, the FOSMC with different orders are presented to verify that the FOSMC can better restrain the chattering phenomenon than traditional integer-order SMC. Simulation results show that the FOSMC can effectively reduce the chattering phenomenon and ensure the power system stabilization in an upper bound time, thus enhancing the dynamic performances of the power system. [ABSTRACT FROM AUTHOR]

• A novel energy storage system based oscillation damping scheme; • A novel PSS/POD node selection approach based on controllability Gramian; • A unit load energy function averaging approach based ESS sizing; • Enhanced system performance under high wind power penetration. This paper proposes a novel power oscillation damping approach for transient stability enhancement of a power system with high penetration of wind power, where the energy storage system (ESS) is utilized to assist the damping of power oscillation with power system stabilizer and power oscillation damper. First of all, the ESS-based power system stabilizer and power oscillation damper structures are proposed to enhance the flexibility of power input and output of the wind turbines and the synchronous generators. Subsequently, the effect of installing ESSs for the enhancement the SGs and WTs' damping torque is analyzed. In the meantime, we proposed an optimal allocation approach to decide the installation nodes of the ESSs by minimizing the Euclidean distance of the system's uncontrollable oscillation modes to its controllability Gramian, along with the optimal sizing approach of ESSs via a novel unit load energy function averaging approach. Simulations are conducted to validate the effectiveness of the proposed scheme, and the superior performance of the proposed approach is also proven via comparative studies. [ABSTRACT FROM AUTHOR]

The hydraulic turbine regulating system (HTRS), which is a core part of hydropower station, is essential and significant for the safe and stabilization operation of the hydropower station. The HTRS is a highly nonlinear, strongly coupled non-minimum phase system, which is difficult and significant to design controller to maintain the frequency stability of the HTRS. In this paper, a fixed-time synergetic controller (FTSC) is proposed to make the frequency of the HTRS stable for small and medium-size power stations in an upper bound time. The input/output feedback linearization is implemented to establish the relationship between the frequency of HTRS and the control input. An FTSC is presented based on the Lyapunov stability theory, synergetic control theory, and fixed-time stability theory. Besides, the proposed FTSC can ensure the frequency stability of HTRS in a limited and quantifiable convergence time, which is not dependent on the initial operating condition and thus overcoming the shortcoming of finite-time stability. Finally, comparative simulations between the proposed FTSC, PID, and sliding mode control (SMC) are presented. Meanwhile, the effects of different hydraulic-mechanical parameters are considered. The results validate the effectiveness and the superior performance of the proposed FTSC over existing PID and SMC under various operating conditions. • A FTSC is proposed for stabilization and chattering-free of the HTRS in small and medium power stations. • The Proof for the frequency stability of non-linear HTRS with the proposed FTSC is presented. • The convergence time which is not dependent on initial operating conditions can be evaluated. • Superior performances of the FTSC are presented by comparing with PID control and SMC. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes an optimization approach for the participation of wind turbines in large scale power systems. The wind turbine participation optimization aims to regulate the droop slopes and the synthetic inertia of the aggregated wind turbines to command the power contribution of wind turbines proportional to their power ratings in the primary frequency response schemes. A reduced second order model of power system is firstly presented to simplify the analysis of large scale power system. Meanwhile, the internal dynamics of general wind turbines are analyzed and the concept of stability margin is proposed to describe the wind turbines' capability of enduring frequency dips at the bus node. A convex optimization based approach is then presented to regulate the droop slopes and synthetic inertia of the wind turbines incorporating their stability margin. Five case studies are conducted in New England 39‐bus system, IEEE 118‐bus power system and the Polish 3375‐bus system. The simulation results indicate that the proposed approach is capable of transiting the bus frequency to the new steady state in a smoother and more stable manner. [ABSTRACT FROM AUTHOR]

Highlights • The series-compensated DFIG-based wind power plant is feedback linearized. • A sliding mode controller is designed based on the feedback linearization model. • The proposed controller shows superior damping performance. • The proposed controller improves disturbance rejection and robustness properties of the system. Abstract This paper presents a robust nonlinear controller based on feedback linearization technique and sliding mode control to alleviate sub-synchronous control interaction (SSCI) in doubly-fed induction generator (DFIG)-based wind farms connected to series-compensated transmission lines. To take full advantage of DFIG converter control, the feedback-linearized sliding mode controller (FLSMC) is designed for rotor side converter (RSC) and grid side converter (GSC) through scrutinizing system linearizability, performing feedback linearization, and designing sliding mode control based on the feedback-linearized system. Eigenvalue analysis and electromagnetic transient (EMT) simulation are carried out to assess the performance of the FLSMC at varied operating conditions, and the capability of the FLSMC in alleviating SSCI is compared to the sub-synchronous resonance damping controller (SSRDC) and proportional-integral (PI) controller. Besides the effectiveness in mitigating SSCI, the FLSMC also improves the robustness of the studied system under external disturbances and parameter uncertainties. [ABSTRACT FROM AUTHOR]

Virtual inertia has been extensively implemented in power systems with distributed energy resources, especially wind energy conversion systems. This paper proposes an optimal virtual inertia planning strategy for stability enhancement of power system, which is penetrated with large volume of renewable resources provided by doubly fed induction generators (DFIGs). The stability of DFIG is first analyzed and the concept of critical frequency drop is proposed. Moreover, the intersection area between the two predefined operation curves of DFIG is defined as the stability margin and it is calculated in the form of a function of local virtual inertia. Subsequently, a virtual inertia planning strategy is proposed, wherein a coherency index that considers the homogeneity of the stability margin at each node is presented, followed by a nonconvex optimization problem. The problem is simplified with the Lyapunov function method and resolved. Two case studies are conducted to verify the effectiveness and performance of the proposed approach: a 12-bus system and the IEEE-118 bus system. Both cases show that with the proposed approach, the system stability margin coherency level is enhanced and the general stability is promoted. [ABSTRACT FROM AUTHOR]

Highlights • A coordinated high-order sliding mode control method. • Power optimization and grid synchronization of a doubly-fed induction generator. • A novel sliding stage reaching law. Abstract This paper aims to propose a coordinated high-order sliding mode control (HOSMC) method for power optimization and grid synchronization of a doubly-fed induction generator (DFIG) based wind energy conversion system (WECS). The super-twisting algorithm is employed to maximize the captured wind energy with optimal rotor speed tracking, and regulate the voltage to fulfill the grid requirement. Subsequently, a grid synchronization scheme is proposed, where the wind turbine stator terminal voltage is controlled to synchronize with the grid voltage without employing the current control loop. Meanwhile, a novel reaching law is employed to accelerate the reaching speed. Simulations are carried out to verify the effectiveness of the novel approach, where the first order sliding mode control and the proportional-integral control are considered for comparison. A stepwise wind speed scenario, a variable wind speed condition, and the scenario under parameter perturbations are included in the comparative study. The simulation results fully reveal the robustness, chattering free property and high tracking precision of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a fractional order sliding mode control (FOSMC) strategy for grid-connected doubly fed induction generator (DFIG). The novel approach aims to directly control the active/reactive power output of a DFIG-based wind energy conversion system with FOSMC, which has never been utilized in the control of DFIG. The fractional order sliding mode control with disturbance is introduced and the Caputo derivative is employed in constructing the sliding surface. Meanwhile, an enhanced exponential reaching law is utilized in order to mitigate the chattering phenomenon in the sliding stage and accelerate the reaching progress in the meantime. A comparative study is conducted subsequently to verify the superior performance of the proposed FOSMC control scheme over that of the conventional sliding mode control and the vector control approach. A steady state simulation is first conducted to tune the parameters of the FOSMC. A variable wind condition is subsequently simulated to compare the performance of those methods. After that, simulations with background harmonics of the grid voltage and parameter perturbation are considered. Ultimately, an experimental test is conducted to further validate the proposed method. The superior performance and the effectiveness of the FOSMC are fully validated with the above four comparative tests. [ABSTRACT FROM PUBLISHER]

• A power system with high wind energy penetration. • A coordinated power system damping framework with PODs and PSSs. • An optimal node selection approach for locating the PSSs and PODs. • An event triggered node augmentation scheme to cope with cascading contingencies. With the increasing penetration of doubly fed induction generator (DFIG) wind turbines in power systems, they should be capable of damping the power oscillations. DFIGs equipped power oscillation damper (POD) combing synchronous generators equipped with power system stabilizer (PSS) are being deployed to damping power system oscillations. However, a major gap in this field is the selection of the optimal controller node in the system. This paper aims to propose an optimal node selection approach for POD and PSS in power systems, assisted by an event triggered node augmentation scheme to cope with cascading system contingencies. A submodular function is constructed to evaluate the distance between the system unstable eigenvectors and the controllability Gramian, and the base input set as well as the candidate nodes are selected. Subsequently, an event triggered condition is formulated to allow the candidate controller nodes to participate in damping the system oscillation. Four case studies are conducted and the results indicate that the proposed approach can effectively select the optimal PSS/POD nodes to improve the performance of the controllers. [ABSTRACT FROM AUTHOR]

• Energy-shaping L 2 -gain controller (ESLGC) is designed for PMSG to mitigate SSI. • Simulation is performed based on aggregated PMSG wind farm and multi-PMSG wind farm. • ESLGC achieves fast mitigation of SSI under various operating conditions. As the serious stability issue of wind power systems, subsynchronous interaction (SSI) problem has resulted in the significant loss of generation. Much effort is put into investigating the risk for SSI in wind farms by manufacturers and research community. To mitigate SSI for permanent magnetic synchronous generator (PMSG), this paper proposes energy-shaping L 2 -gain controller (ESLGC) for machine side converter (MSC) and grid side converter (GSC). ESLGC not only assures the global asymptotical stability but also enhances system robustness against disturbances. An aggregated series-compensated PMSG-based wind farm and a multi-PMSG wind power system are adopted to evaluate the effectiveness of ESLGC. The results of eigenvalue analysis and time-domain simulation show better robustness and damping performance of the proposed ESLGC as compared to conventional PI controller and filter-based subsynchronous damping controller (SSDC) under various operating conditions. [ABSTRACT FROM AUTHOR]

• A specified time consensus control approach for energy storage system. • A coordination strategy to engage wind turbines and ESSs in frequency support. • A delay margin estimation approach to assess the control signal delay boundary. Small scale energy storage systems (ESSs) can assist grid integration of doubly fed induction generators (DFIG), potentially in power system frequency regulation. However, the extensive communication between ESSs may cause frequency response delays and may deteriorate the performance. Thus, this paper aims to propose a frequency response scheme with ESS assisted DFIGs wind turbines (WTs) via a specified time consensus (STC) approach. The load frequency control model with high penetration of WT is firstly constructed. A delay margin estimation (DME) procedure is conducted afterwards to estimate the allowable time delays for the system to provide frequency response. Meanwhile, the coordination strategy of the WTs and the ESSs is proposed for load sharing among the WT-ESS. Subsequently, the STC control for the ESSs is proposed to achieve consensus among the ESSs within a specified time requirement induced by the delay margin. Simulations are conducted to validate the effectiveness of the proposed method. The simulation results show that the DME is meaningful for shaping the allowable system time delay; the STC control can effectively smooth the power output of WTs and enhance the frequency regulation capability; comparing with conventional methods, the novel method shows faster convergence speed and better frequency regulation performance. [ABSTRACT FROM AUTHOR]

This paper proposes an event triggered sliding mode control method for direct power control (DPC) of doubly fed induction generator (DFIG). Conventional control approaches require the execution units to constantly update the control signal from the computing devices, which is unnecessary and requires extra communication and execution efforts for the control system. The event triggered control is able to determine the optimal time nodes to update the executed control signal with the event triggering condition. The event triggered mechanism is utilized in sliding mode control and the proposed method is employed for DPC of DFIG. Meanwhile, the prescribed time convergence principle is adopted for parameter selection of the controller. Subsequently, an extended state observer is designed to provide disturbance rejection capability for the DFIG. The Laypunov function method is employed to prove the convergence and stability of the system. Simulations and experimental studies are conducted to validate the performance of the proposed method. The experimental results indicate that the proposed method has superior performance in tracking precision, robustness against parametric disturbance and resource saving. [ABSTRACT FROM AUTHOR]

In this paper, a distributed predefined-time fractional-order sliding mode controller (DPTFOSMC) is proposed for performance improvement of power system. The proposed DPTFOSMC is designed based on the multi-agent framework and distributed control theory, which can reduce the pressure of central controller in communication and calculation, thus obtaining fast and coordinated response. The DPTFOSMC can achieve the advantages of sliding mode control (SMC) with fast response and strong robustness for the power system. In addition, the power system under the proposed DPTFOSMC can be stabilized in stable range within a predefined time which is directly equal to the tunable parameter, thus meeting the high requirement for convergence time of the power system. The prescribed performance function (PPF) is carried out to design the DPTFOSMC, which can ensure that the power system can achieve the expected transient and steady responses. Meanwhile, fractional calculus is implemented to devise the DPTFOSMC to eliminate the chattering phenomenon of conventional SMC. The Lyapunov function is adopted to analysis the predefined-time stability of the power system under the proposed DPTFOSMC. Simulations are taken to validate the effectiveness and superior performance of the proposed DPTFOSMC for the power system. The results show that the DPTFOSMC can ensure the power system to achieve superior performances than the existing control methods. [ABSTRACT FROM AUTHOR]

• A discrete prescribed time consensus for robust convergence time control. • An optimal leaders selection scheme to tackle leader corruption issues. • An event triggered communication protocol in battery communication networks. Small scale energy storage systems (ESSs) can serve as buffers for integrating renewable energy resources into the main grid. Their available energy can be aggregated to provide ancillary services for power systems. This paper considers a load frequency control (LFC) scheme with energy storage aggregator comprises of ESSs. To coordinate the behaviors of ESSs for LFC support, a discrete prescribed time consensus control is proposed which ensures that the ESSs can reach consensus within the prescribed settling time. To improve the tracking precision, an optimal leader set is selected with submodular optimization. In the meantime, an event triggered communication (ETC) protocol is proposed to reduce the unnecessary information sharing among ESSs. The ETC protocol is naturally Zeno free with the defined sampling instants. Case studies are conducted to validate the effectiveness of the proposed method, and the performance of the proposed method is superior than conventional and state-of-art methods with comparative studies. [ABSTRACT FROM AUTHOR]

• A high-order sliding mode based direct power control (HOSM-DPC) scheme for doubly-fed induction generator. • A power compensation strategy for DFIG wind turbine under unbalanced grid voltage condition. • A novel power compensation strategy for DFIG with variable wind speed scenario. • A Lyapunov function based super-twisting algorithm for parameter design. This paper proposes a novel high-order sliding mode (HOSM) based control methodology for direct power control (DPC) of doubly-fed induction generator (DFIG) wind turbine which is operating under unbalanced grid voltage conditions. Firstly, a set power quality enhancement strategies are presented, incorporating six power compensation schemes corresponding to six selective control targets in both steady and variable speed conditions. Meanwhile, the DFIG output powers are regulated with the proposed HOSM-DPC scheme, wherein a super-twisting algorithm is employed to cope with the chattering phenomenon and simplify the controller structure. The Lyapunov function method is utilized to decide the stability region of the controller parameters. Experiments and simulations are conducted to prove the validity and the performance of HOSM-DPC, where the DPC method with lookup table and the first order sliding mode based DPC are incorporated for comparison purpose. The experimental tests fully reveal the effectiveness of HOSM-DPC in power quality improvement subjected to unbalanced grid voltage conditions, and the superior performance of HOSM-DPC in dynamic response, chattering phenomenon elimination and variable wind speed operation are also validated. [ABSTRACT FROM AUTHOR]

This paper proposes an adaptive droop gain-based consensus approach for reactive power sharing in microgrids (MGs) with the event triggered communication protocol (ETCP). A multi-agent system-based network is constructed to establish the communication with distributed generators (DGs) in MGs. An ETCP is proposed to reduce the communication among agents to save resources and improve system reliability, as the communication is only needed when the event triggered condition is fulfilled. A stability analysis is conducted to guarantee the existence of the equilibrium point and the freeness of the Zeno solution. Moreover, an adaptive droop gain is designed to reduce the impact of imbalanced feeder impedances. Four case studies are conducted to verify the effectiveness and performance of the proposed method. The simulation results show that the ETCP-based approach is capable of achieving power sharing consensus, communication reduction and shifting the information exchange mode based on the operation scenarios. [ABSTRACT FROM AUTHOR]

• A multi-objective renewable energy management scheme is proposed. • Cost saving, green consumption and power quality are the main motivations. • A novel multi-agent system with three electricity use mode is developed. • Key implications and recommendations for policy makers are given. This paper proposes a multi-objective renewable energy management scheme to satisfy the needs of diversified community power consumers, wherein the multi-agent system is employed for coordinating and controlling the power generation and consumption units. Firstly, a multi-agent based microgrid and home energy management system is constructed. Subsequently, system models for renewable energy sources, electrical vehicles, residential loads and the cost function are constructed to form the microgrid operation constraints. With these constraints, three optimization models are proposed to minimize the electricity bills, the power purchased from the main grid, and optimize the power quality. The three objectives are proposed to reflect the power consumer's needs for cost saving, green consumption, and power reliability, respectively. Meanwhile, a coordination strategy which balances the three objectives is proposed. After that, a novel multi agent system is proposed to realize the proposed objectives. Four case studies and a sensitivity analysis are conducted to verify the effectiveness of the proposed method. The case study results show that: in electricity minimization, 2–6.5% of total electricity bills can be saved; in main grid power consumption minimization, the peaks of the power consumption profiles are shaved while the valleys of the profiles are filled; in power quality enhancement, the steady state frequency drop is reduced for 0.35 Hz to 0.38 Hz. The sensitivity analysis shows that communities equipped with energy storage systems accounting for 30% of the total load can achieve best optimization outcomes; the increase in renewable energy usage will lead to higher electricity bills and poorer power quality if the renewable energy sources are limited, while the availability of more renewable energy sources will compensate for the negative effects of using renewable energy sources. [ABSTRACT FROM AUTHOR]

• A fractional order sliding mode control method for power quality enhancement of the (PMSG) wind turbine is proposed. • Two fractional order sliding mode controller are employed to control the MSC and GSC. • The Lyapunov function based stability analysis is conducted. This paper proposes a fractional order sliding mode control (FOSMC) method for permanent magnet synchronous generator (PMSG) to enhance its output power quality. The control scheme concludes the machine side converter (MSC) control and the grid side converter (GSC) control. In the MSC, the rotor side d-q axis currents are controlled by a novel fractional order sliding mode controller; in the GSC control, the output voltage and the DC-link voltage of the GSC are regulated by another fractional order sliding mode controller. Moreover, a stability analysis based on Lyapunov function is conducted to decide the controller coefficient boundaries. The gravitational search algorithm is used to obtain the optimal parameters. Subsequently, three simulations and three experimental case studies are conducted to show the effectiveness of FOSMC, and the performance of FOSMC is compared with conventional sliding mode control and proportional integral control methods. The simulation and experiment results reveal that FOSMC has faster time response, superior tracking precision in both steady state and variable wind speed conditions, and it shows stronger robustness against parametric disturbances over SMC and PI control. [ABSTRACT FROM AUTHOR]

Increasing use of series compensation in doubly-fed induction generator (DFIG)-based wind farms has led to subsynchronous control interaction (SSCI) incidents. The irregular exchange of energy between the network side and generator side is considered responsible for SSCI. Therefore, an energy-shaping controller (ESC) is proposed in this paper to mitigate SSCI from the energy perspective. Firstly, based on energy relationship and physical nature, Hamiltonian model is established to describe the system structure. Secondly, the controller is obtained by solving the energy equation. Damping is then injected into the controller dynamics and it is back-propagated to the system, ensuring the global asymptotical stability. Thirdly, the controller is further improved to make gamma-dissipation inequality hold, thereby enhancing the robustness. Time-domain simulation and impedance model (IM)-based stability analysis are conducted to evaluate the damping performance of ESC. Simulation results demonstrate the effectiveness of ESC under a wide range of operating conditions. Moreover, ESC also improves system robustness against external disturbance and parameter uncertainty. [ABSTRACT FROM AUTHOR]

This study proposes a robust sub‐synchronous damping controller based on fractional‐order sliding mode control (FOSMC) method to mitigate sub‐synchronous control interaction (SSCI) induced by DFIG‐based wind park connected to series‐compensated transmissions. Firstly, the nonlinearity of DFIG is cancelled through feedback linearisation. Secondly, FOSMC is designed and applied to the control loop of the DFIG rotor‐side converter. During the design process, the extra degree of freedom, provided by the fractional operator, is employed to achieve fast SSCI‐damping. Thirdly, a genetic algorithm is used for parameter optimisation with the aim of making system eigenvalues approach the left plane. The effectiveness of the proposed damping controller is evaluated based on the adapted IEEE first benchmark model, non‐aggregated wind system model with a realistic configuration, and experimental platform. Simulation and experiment results demonstrate the superior damping performance of FOSMC under different wind speeds, compensation levels, and the number of online wind turbines. Moreover, FOSMC also shows the robustness under parameter uncertainty, control parameter perturbation, and symmetric (three‐phase short circuit) fault. [ABSTRACT FROM AUTHOR]

In AC microgrids (MGs), the required high control gain for dealing with control faults would reduce the robustness of the secondary control to communication constraints. To tackle with this problem, the subarea physical infrastructure of AC MGs and the two-layer secondary control framework are designed. For the physical infrastructure, the whole AC MG is divided into several areas, where each area is composed of a distributed generator (DG) and several geographical-close loads. Furthermore, by utilizing the advanced metering infrastructure (AMI), loads transmit the local load change information to the DG in the same area. Based on this physical infrastructure, a distributed event-triggered fixed-time fault-tolerant (ET-FTFT) secondary control framework is proposed in this paper to improve the resilience of the secondary control to sensor and actuator faults/attacks, and communication constraints, simultaneously. The adopted two-layer control framework is to decouple the communication constraints and control faults. The event-based strategy is adopted in the upper layer to reduce the communication burden and Zeno behavior can be evaded. Real-time simulations based on the NI-PXI real-time simulator validate the advantages of the distributed ET-FTFT secondary control framework, which are the better robustness to control faults, and the fixed-time convergence to improve the power quality. [ABSTRACT FROM AUTHOR]

• Proposed agents-based MEGG for the generation of electrical power. • The finest strategy to generate energy with lower emissions and generation costs. • Agents-based supervision technique to make the grid more efficient and reliable. • A novel distributed energy management system to attain higher grid efficiency. • Optimal scheduling and trading of energy to satisfy load demands competently. Due to high environmental concerns and ever-increasing fossil fuel costs, generation of clean energy and its optimal management considering the demand side responses are very essential to upsurge the productivity and reliability of the distribution grids. Hence, a kind of distributed microgrid identified as multi-energy generation grid (MEGG) has been proposed in this paper. The anticipated MEGG integrated with renewable energy resources, fuel cells (FCs), an alternative grid-supporting generator (AGSG) connected with boiler, micro-turbine (MT), and thermal system, wastes burning power plant (WBPP), and energy storage system (ESS) that investigate the optimal resource management in a grid under various operational conditions to minimize the emissions and operational costs. The problem is supervised by agents-based technique considering the generation capabilities and demand side responses. The three-layered technique is presented for the distributed optimal resource management based on multi-agent systems (MAS) framework, where different agents operate and perform tasks autonomously. An optimal energy management scheduling strategy is accomplished considering actions that guarantee the maximum use of generated renewable energy, eradicate the excess use of WBPP and FC, minimize AGSG operational time, and full-load demands satisfaction during the entire day. Similarly, coordination between the MEGG and central power grid has also been accomplished for the purpose to exchange power. For validation, three scenarios have been presented which shows that the combined utilization of distributed energy resources can profusely generate electricity having less emissions, recover the generation costs in peak hours, and enhance the reliability of the entire grid. [ABSTRACT FROM AUTHOR]

A sliding mode control (SMC) scheme of doubly fed induction generator (DFIG) wind turbine with a novel exponential reaching law (NERL) is proposed in this paper. The DFIG wind turbine is running under variable wind speed. The NERL based SMC proves to be capable of reducing the system chattering phenomenon as well as accelerating the approaching process. A nonlinear case numerical simulation test is employed to verify the superior performance of the ERL method over traditional power rate reaching strategy. The NERL based SMC is employed to control the DFIG wind turbine generator under variable wind speed subsequently and the simulation results evidence the remarkable performance of the NERL based SMC control scheme. [ABSTRACT FROM AUTHOR]

Non-Intrusive Load Monitoring (NILM) is an energy-saving technology that has been widely concerned. It can estimate detailed energy consumption information from aggregated power data, eliminating the need to install sub-meters on individual appliances. In addition to the power consumption information from each appliance, traditional load monitoring algorithms often require additional information to help train the model, which incurs extra user interaction during the modeling process, limiting the wide application of NILM. In this paper, we presented a novel model named Adaptive Factorial Hidden Markov Model (Adaptive-FHMM) to characterize the transition between working states of each appliance. In the proposed model an adaptive clustering process is introduced, which could automatically determine the number of hidden states according to the power variation at different working stages. Then the working states information of each appliance is utilized to build a combined model to predict the appliance's power consumption. Experiments are conducted on two publicly available datasets and one dataset collected from the laboratory, and the results show that the proposed model outperforms five state-of-the-art models in the metrics of energy-based F1, Mean Absolute Error(MAE), and Match Rate. Specifically, the proposed Adaptive FHMM model achieves 26.8% and 52% reduction in MAE compared to the second-best model on the real-world dataset of REDD and AMPds, respectively. • A parameter free model is proposed to model the multi-state appliance more accurately. • The proposed model determines the appliance's working states based on its power data adaptively. • Experiments on multi-states dataset and real-world datasets demonstrate the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

• A FTFOSMC is proposed for performance enhancement of the PMSG wind turbine. • The proof is presented for the stabilization of the PMSG wind turbine under the proposed FTFOSMC. • The upper limited convergence time of the PMSG wind turbine under the FTFOSMC can be estimated. • The simulations are taken to validate the superior performance of the PMSG wind turbine under FTFOSMC. This paper proposes a fixed-time fractional-order sliding mode controller (FTFOSMC) for the permanent magnet synchronous generator (PMSG) wind turbine to enhance the power quality. The FTFOSMC is implemented in the rotor side converter (RSC) and the grid side converter (GSC) to stabilize the PMSG wind turbine within an upper limited convergence time and to improve the dynamic performances. The fractional-order calculus is taken to devise fractional-order controller and the expression of the FTFOSMC is a continuous description, which can better weaken the chattering phenomenon of conventional SMC. Meanwhile, fixed-time stability is adopted to ensure the stabilization of the PMSG wind turbine within an upper limited convergence time irrelated with the initial states. The detailed proof is presented to validate that the proposed FTFOSMC can ensure the PMSG wind turbine stable and estimate the upper limited convergence time through Lyapunov function. Finally, several cases, including peak power tracking and reactive power control, variable wind speeds, grid voltage disturbances and experimental verification, are studied to show the effectiveness, robustness and superiority of the FTFOSMC than the PI control. Simulation and experimental results show that the FTFOSMC can achieve superior dynamic performances than the PI control with shorter convergence time, less vibration, higher tracking accuracy and stronger robustness, thus improving power quality of the PMSG wind turbine. [ABSTRACT FROM AUTHOR]