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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 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]