This paper presents the development of a single-phase grid-connected wind energy conversion system (WECS) that uses a modified PLL. The WECS development is based on the use of the low cost 30 MIPS Digital Signal controller (DSC) dsPIC30f3011. The modified single-phase PLL is based on the PQ theory, where a lag structure based on an integrator is proposed instead of a conventional lag structure. The voltage source inverter (VSI) is driven by a Space Vector Pulse Width Modulation (SVPWM). The maximum power transfer is achieved by using a Maximum Power Point Tracking (MPPT) algorithm based on the steepest ascent method. The tasks related to the SVPWM algorithm, the PLL, the MPPT algorithm, and the monitoring of the DC voltage were successfully implemented in the DSC. Index Terms-Digital signal controller, inverter, maximum power point tracking, permanent magnet generator, space vector modulation, wind power generation.

This paper presents a novel Parameter-Independent Fictive-Axis (PIFA) approach for the Voltage-Oriented Control (VOC) algorithm used in grid-tied single-phase inverters. VOC is based on the transformation of the single-phase grid current into the synchronous reference frame. As a result, an orthogonal current signal is needed. Traditionally, this signal has been obtained from fixed time delays, digital filters or a Hilbert transformation. Nevertheless, these solutions present stability and transient drawbacks. Recently, the Fictive Axis Emulation (FAE) VOC has emerged as an alternative for the generation of the quadrature current signal. FAE requires detailed information of the grid current filter along with its transfer function for signal creation. When the transfer function is not accurate, the direct and quadrature current components present steady-state oscillations as the fictive two-phase system becomes unbalanced. Moreover, the digital implementation of the transfer function imposes an additional computing burden on the VOC. The PIFA VOC presented in this paper, takes advantage of the reference current to create the required orthogonal current, which effectively eliminates the need for the filter transfer function. Moreover, the fictive signal amplitude and phase do not change with a frequency drift, which results in an increased reliability. This yields a fast, linear and stable system that can be installed without fine tuning. To demonstrate the good performance of the PIFA VOC, simulation and experimental results are presented.

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