Normalized Maximum Correntropy Criterion Based Ripple Mitigation Strategy for Wind–Solar Hybrid Generation System Under Nonideal Grid Conditions

A doubly-fed induction generator (DFIG) integrated to a solar photovoltaic array for wind-solar hybrid power generation, exhibits large multiple-order ripples in DFIG torque as well as active and reactive grid powers, when subjected to a nonideal grid voltage scenario. In this context, this article aims to develop a ripple mitigation strategy based on a novel application of the normalized maximum correntropy criterion (NMCC). The NMCC-based strategy puts forth a comprehensive solution toward mitigating all the ripples emanating either due to voltage unbalance in the grid, or due to grid voltage distortions with both positive and negative sequences of any possible harmonic order. Additionally, the power ripples originating from unbalanced and nonlinear loads interfaced locally to the wind-solar hybrid system are also compensated. The strategy is devised to be parametrically robust and does not necessitate individual harmonics separation in either fluxes, voltages, or currents. Besides, need for inner loop PI, PR, or other complex regulators is also eliminated. Moreover, the control scheme is formulated as a modular structure to ensure distortion-less DFIG rotor currents and balanced-sinusoidal grid currents at nonideal voltages, even as the ripple mitigation loops are disabled. Experimental results from a laboratory test bench verify the effective operation of the NMCC-based control strategy.

I. Introduction

Owing to universal acceptance toward sustainable power generation as the only solution for rising energy demand and climate change issue, distributed generation with multiple renewable energy sources, has attracted wide attention among researchers. A critical requirement for such systems, especially in remote and secluded areas, is the capability of retaining self-sufficient generation for the locally interfaced loads. In this regard, due to their inherent complementary generation cycles, wind- and solar-based hybrid power generation system (HPGS) has emerged as an optimal configuration [1]. Solar photovoltaic (SPV) array is the obvious choice for solar power generation. Meanwhile, due to its outstanding merits such as reduced rating power converters, variable speed constant frequency active power generation, controlled reactive current injection ability, relatively uncomplicated design, and cheap production cost, the doubly-fed induction generators (DFIGs) have become the leading technology for the wind turbine-driven generators [2].