This paper proposes a distributed control architecture for battery energy storage systems (BESSs) based on multi-agent system (MAS) framework. The active/reactive power sharing, the frequency/voltage, and the energy of BESSs are synchronized by exchanging local information with a few other neighboring BESSs. Two consensus algorithms namely leaderless and leader-follower are proposed. The proposed control architecture offers unique features. Firstly, the heterogeneous nature of BESSs is explicitly taken into account in BESS models and consensus designs, while it is usually ignored in the literature. Secondly, the proposed designs bring the plug-and-play capability to the smart grid system by operating in both islanded and grid-connected modes. Next, the nominal frequencies and nominal voltage magnitudes of BESSs are used in the consensus design instead of their frequencies and voltage magnitudes. This makes the proposed structure much easier to be implemented in the real power grids. Lastly, an additional control input is designed to synchronize the energy levels of BESSs directly, whereas the energy levels of BESSs are synchronized indirectly through their powers in other existing research. Time-domain simulations on a modified IEEE 57-bus power system are then carried out to validate the proposed control structure and the consensus designs.

This paper proposes a day-ahead market framework for congestion management in smart distribution networks. The presented scheme provides a platform for collaboration between distribution-level market operator (DMO) and data traffic operator (DTO) to alleviate congested feeders such that data transmission traffic between market participants is effectively managed in a smart grid. In addition, a decentralized mechanism is developed for collaboration of electric vehicle (EV) aggregators with common clients to take advantage of EVs not only as flexible loads but also as mobile distributed storage (MDS) for congestion management. Moreover, the proposed framework outlines an administrative action for distribution system operator (DSO) to support the market when the decentralized competitions among distributed generation (DG) aggregators and EV aggregators do not fully relieve a serious congestion. The proposed day-ahead congestion management scheme is validated on an unbalanced 136-bus distribution system massively integrated with wind turbine DGs (WTDGs), photovoltaic DGs (PVDGs), diesel-engine DGs (DEDGs), and EVs.

This paper employs impedance model-based frequency domain analysis to detect subsynchronous resonances (SSRs) in Type-3 wind farms with thyristor-controlled series capacitor (TCSC). The contributions of this paper are 1)the derivation of dynamic phasor-based TCSC impedance model and 2)the application of such an impedance model in Type-3 wind energy systems for SSR analysis. Impedance models for TCSC with constant firing angle control and impedance control are derived in this paper. With the derived impedance models, Nyquist stability criterion is applied to compare SSR stability in Type-3 wind farm with TCSC or with fixed capacitor compensation. This paper employs analytical models to demonstrate TCSCs capability in avoiding SSR in Type-3 wind generator interconnection systems. The analytical results obtained through impedance models are validated by detail model-based (with thyristor switch-modeled) time-domain simulation in MATLAB/SimPowerSystems.

In this paper, consensus integral control is applied for energy storage in microgrids to synchronize the state-ofcharge (SoC) and power levels of batteries with limited information exchange. Both local information (SoC and power level) and neighbors’ information (SoC and power level) will be fed into an integral control installed at every battery converter. The design is based on consensus control and takes into consideration of realworld battery coordination requirements, e.g., all batteries should work in the same charging or discharging mode. Compared with the consensus control in the existing literature for voltage consensus or battery SoC/power consensus, this paper offers a simple design. The major assumption of the paper is that each converter should possess an integral control. This assumption is valid since indeed integral controls exist if converters are equipped with secondary frequency control. The designed consensus control is validated by simulations on 14-bus microgrid and IEEE 57-bus power system. Simulation results demonstrate the effectiveness of the consensus integral control for variety modes of operation: charging, discharging, and load variation.

This paper investigates the stability of a modular multi-level converter (MMC)-based HVDC system connected to a weak ac grid. Impedance analysis is used to study the interactions between the weak ac grid and the converter. For this, the impedance of the MMC is first derived considering various outer- and inner-loop controllers. The Nyquist-stability criterion is then used to analyze the stability of the MMC connected to the weak ac grid for various case studies. The impact of circulating current controller on the stability of the MMC connected to the weak ac grid is also validated for two different types of outerloop controllers. Finally, time-domain simulations are carried out using MATLAB/Simscape Power System toolbox to validate the analytical results