Improved Multi-Layer GI-QSG Control for Grid-Interactive SPVA-BES-SyRG Wind Based Microgrid

Abstract

In this work, a control algorithm is implemented for power quality enhancement in the grid-interactive micro grid, operating with nonlinear/unbalanced loads. The microgrid consists of the solar photovoltaic array (SPVA) and battery energy storage (BES), and a synchronous reluctance generator (SyRG) based wind energy system (WES). Both energy sources interact with the AC grid at PCC through a single voltage source converter (VSC) and the back-to-back VSCs, respectively. This work implements the improved multi-layer generalized integrator (GI)- quadrature signal generator (QSG) to separate the positive and negative sequence components (PNSC) for the sensed load currents fundamental component (FC) and the harmonics components (HC). These estimated components are practiced to control the grid side VSC's currents for both the energy sources to eliminate the harmonics and negative sequence currents from the injected grid currents and adhere to the IEEE std 519 at the PCC. Moreover, the SPVA-BES system currents are controlled so that no negative sequence currents flow in its VSC, eliminating the requirement of an additional converter to protect the BES from the second harmonic current. The same algorithm is exercised to evaluate the PNSC for the AC grid voltages and in the sensorless field-oriented control (FOC) of the SyRG in the WECS. Further, in the FOC, the SyRG direct axis current is controlled to minimize the winding losses to acquire maximum efficiency. Performance of the control algorithm is corroborated on a microgrid model, developed using MATLAB /Simulink and subjected to the nonlinear/unbalanced loads, varied solar insolation, and wind speed conditions.