Selecting between Linear and Nonlinear Control in a Dynamic Voltage Restorer

This paper presents the comparison of two control techniques, tested in a dynamic voltage restorer (DVR). Linear and nonlinear control schemes are compared in terms of system modeling, dynamic response, signal tracking, stability, and implementation. Mathematical, analytical, and practical simulation results demonstrate that nonlinear control allows a better compensation performance under transient and steady state operating conditions. The implemented nonlinear scheme is a passivity based control (PBC), whereas the linear control is implemented with the traditional PI. This paper validates that the passivity based nonlinear control is a better and feasible alternative for converter applications, especially when fast dynamic response, zero steady state error, changes of operating points, no overshoots on the controlled signal, and an easy implementation are required. The application on dynamic voltage restorers can be extended to other active compensation equipment implemented with static converters.