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Solar panels are an attractive and growing source of renewable energy in commercial and residential applications. Its use connected to the grid by means of a power converter results in a grid-connected photovoltaic system. In order to optimize this system, it is interesting to integrate several functionalities into the power converter, such as active power filtering and power factor correction. Nonlinear loads connected to the grid generate current harmonics, which deteriorates the mains power quality. Active power filters can compensate these current harmonics. A photovoltaic system with added harmonic compensation and power factor correction capabilities is proposed in this paper. A sliding mode controller is employed to control the power converter, implemented on the CompactRIO digital platform from National Instruments Corporation, allowing user friendly operation and easy tuning. The power system consists of two stages, a DC/DC boost converter and a single-phase inverter, and it is able to inject active power into the grid while compensating the current harmonics generated by nonlinear loads at the point of common coupling. The operation, design, simulation, and experimental results for the proposed system are discussed.

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In this paper, a di/dt detection circuit for DC breaker applications is proposed to provide faster short-circuit and overcurrent fault detection, where DC breakers are required to be designed for unidirectional fault current conditions, which is a challenge regarding DC microgrid applications due to some associated problems such as long periods of fault interruption, complex circuit structure, and low reliability. The proposal, which is based on measurement of di/dt, can detect fault current conditions for different distances from the point of failure, and is suitable to operation in both islanding and grid-connected conditions. The proposed circuit was studied theoretically and experimentally in steady state, as well as under load changes and short circuit conditions to ensure proper operation, making this solution a fast current fault detection solution, which is a significant advantage and requirement in DC microgrid applications.