A New Design of Wide-Area MIMO Coupling Robust HVDC Supplementary Controller

A new multi-input multi-output (MIMO) robust coordination approach for the controller design of multi-infeed high voltage direct current (HVDC) system is proposed. This design will enhance the damping of certain low frequency oscillation mode. The dominant mode ratio (DMR) is applied to choose the appropriate feedback signals, while time delay of wide-area signals is considered. The Total Least Squares-Estimation on Signal Parameters via Rotational Technique (TLS-ESPRIT) algorithm serves in identifying the MIMO system model. To reach the best control effect and disturbance suppression level, the mixed H-2/H robust theory with regional poles placement is introduced to design the controller. The new MIMO design approach avoids system decoupling in complex situation, and it uses the interactions of different control loops to enhance the system's stability when most MIMO HVDC controllers are designed by decoupling strategy. Simulation results of a multi-infeed HVDC system validate the control effect and robustness of the proposed method.