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This paper introduces, explains, and investigates the application of a transformerless series-connected reactive/harmonic compensator. The proposed compensator is applied to compensate the high reactive-power/harmonic demand of a 12-pulse line-commutated HVDC rectifier terminal. Simulation results reveal that the proposed strategy compensates the reactive power and harmonics of the HVDC converter satisfactorily. All of this is achieved using significantly smaller capacitance at the compensator dc link than the capacitance required in the state-of-the-art shunt compensators employing passive components. The compensator thus would eliminate the need of fundamental-frequency reactive power supply and minimize (or eliminate altogether) the requirement of passive shunt harmonic compensation. This would result into smaller shunt passive filters, smaller or no shunt capacitor banks, and smaller converter transformers, leading to a more compact HVDC terminal, the current size of which is considered to be the main hurdle in its application for integration of large-scale offshore wind energy. Experimental results from a small-scale setup validate the effectiveness observed in the simulations. [ABSTRACT FROM PUBLISHER]

In wave energy converters (WECs), the maximum power extraction would be achievable at the expense of a very high rating of the electric and power electronics equipment. The goal of this paper is to show how a convenient tradeoff between high-power extraction and viable electrical device rating can be achieved by a proper choice of the WEC control strategy. Referring to a direct coupled point absorber in heave operating in regular waves, it will be analytically shown how most common control techniques impact on both the power performance and the power takeoff (PTO) rating. Thus, a tool that can assist in the preliminary PTO sizing by taking into account the main constraints imposed by the application is obtained. Following, an adaptive control strategy including a reactive component is proposed, whose goal is to improve the overall system performance when the WEC is already operative in the sea. Its effectiveness in increasing the average power extraction while respecting the PTO peak power constraint is proved by computer simulations in both regular and irregular waves, and specific analyses also including the PTO force/torque limitation are finally developed. [ABSTRACT FROM PUBLISHER]