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Integration of wind energy sources into the distribution grid affects the voltage profile that could be stabilized through the grid reinforcement or limiting the active power injection. This paper presents a control strategy to regulate the voltage at point of common coupling (PCC) through reactive power exchange to the grid. The reactive power capability of the grid-connected hybrid multilevel converter is based on the voltage sensitivity of the distribution grid at PCC. A hybrid five-level multilevel converter referred as flying capacitor (FC) based active-neutral-point-clamped (ANPC) converter is considered. It is an arrangement of a three-level ANPC converter and a two-level cell. Also, a control strategy is proposed to regulate the FCs voltages of the grid-connected hybrid multilevel converter at their required values. The proposed FC control strategy provides extra freedom to regulate the dc-link capacitor voltages with dc-offset injection technique. Simulation studies demonstrate the performance of the proposed control strategies for the system considered. [ABSTRACT FROM PUBLISHER]

The installed capacity of grid connected PV plants has increased significantly over the past few years and is expected to continue its growth over the next decade due to the continuous demand for renewable energy and distributed generation systems. This paper presents a seven-level flying capacitor (FC) based active neutral point clamped (ANPC) converter for the connection of utility-scale PV system to the electricity grid. The multilevel voltage output of the topology provides high quality waveforms while maintaining the operational characteristics of NPC based converters for PV systems. The converter topology together with a method to regulate the FC voltages to their reference values and an optimal third harmonic injection for utilization of the DC-link voltage are presented. Simulation results for the operation of the grid connected converter under steady state and transient operation are provided in order to demonstrate the operation and performance of the topology in grid connected applications. [ABSTRACT FROM PUBLISHER]

The flying capacitor (FC) based active neutral point clamped (ANPC) converter is a hybrid multilevel converter topology, as a combination of the three-level ANPC converter and a number of FC cells. This paper presents a generalized modulator for the seven-level FC based ANPC converter. The proposed modulator is applied independently in each phase of the converter and selects the switching states based on the deviation of the FC voltages from the reference value in order to maintain the FCs and the neutral point voltage of the converter balanced. The modulator is independent of the modulation technique selected for the converter and can operate under both sinusoidal and selective harmonic elimination pulse width modulation. Simulation results for both modulation techniques indicate the operation of the converter while regulating the FC and NP voltages to their references under steady state and dynamic changes and illustrate its effectiveness. [ABSTRACT FROM PUBLISHER]