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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 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]

• 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]

• 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 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]