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Renewable energy sources are growing in importance and reshaping power systems through microgrid (MG) networks. Some relevant issues in the management of an MG need to be addressed, such as voltage and frequency control, power balance between sources (sharing) and distributed loads, stability, security, power quality, etc. As a contribution, this manuscript presents a power management of AC MGs based on concepts of microeconomics theory for market equilibrium. The prices of active and reactive energy are informed through the AC voltage parameters such as magnitude, frequency and angle. This approach allows several sources and loads to operate with no extra communication interface. Experiments are provided to validate operation in many different operational scenarios using a hardware-in-the-loop environment. [ABSTRACT FROM AUTHOR]

This paper proposes a control system for the single-phase Three-Ports Active Neutral- Point-Clamped (ANPC-3P) converter, which can inject a sinusoidal current into the grid, balance the neutral point voltage, and regulate the energy storage system (ESS) current with reduced low-frequency ripple. Despite other applications, ANPC-3P inverter can be used in grid-tied renewable generation to allow the simultaneous connection of a photovoltaic (PV) energy source and an ESS to the AC grid. The ESS is connected directly to the inverter circuit without any auxiliary DC-DC converter, but due to the DC bus pulsed power, it can be subjected to low-frequency current ripple. This undesired current ripple is difficult to filter and can lead to shorter battery life. A control system based on well-known controllers is analyzed and designed. Theoretical analysis is validated experimentally using a single-phase 1-kW prototype. [ABSTRACT FROM AUTHOR]

Voltage profile is one of many aspects that affect power quality in low-voltage distribution feeders. Weak grids have a typically high line impedance which results in remarkable voltage drops. Distribution grids generally have a high R/X ratio, which makes voltage regulation with reactive power compensation less effective than in high-voltage grids. Moreover, these networks are more susceptible to unbalance and harmonic voltage disturbances. This paper proposes an enhanced coordinated control of active and reactive power injected in a distribution grid for voltage regulation. Voltage drop mitigation was evaluated with power injection based on local features, such loads and disturbances of each connection. In order to ensure disturbances rejection like harmonic components in the grid voltages, a repetitive vector-control scheme was used. The injection of coordinated active and reactive power with the proposed control algorithm was verified through simulations and experiments, demonstrating that it is a promising alternative for voltage regulation in weak and low-voltage networks subject to inherent harmonic distortion. [ABSTRACT FROM AUTHOR]