Unified Robust Control Design for BTB-VSC Subject to Uncertainties in Grid Equivalent Circuit

Abstract

This paper presents the design of a unified model and control system for a voltage source converter (VSC)-based Back-To-Back (BTB). The controller based on robust pole placement is designed taking into account that the BTB converter deals with bidirectional power flow and uncertainties related to grid equivalent resistance and inductance at the Point of Common Coupling (PCC). Non-linear and linearized models for the BTB converter along with the design of a state feedback control are presented in a state-space formulation. A BTB-VSC system is assembled and tested in a digital environment. Results for simulations performed are presented showing that the controller can meet desired performance requirements for bidirectional power flow and for different grid equivalent impedance values. Index Terms—Back-to-Back, Voltage Source Converter, Robust Control, Multi-variable Control.