A Comparison of Two Methods for Preventing Pole-zero Cancellation in H∞ Power System Controller Design

This paper compares two techniques that are commonly used to prevent the pole-zero cancellation phenomenon inherent to the Riccati-based H_infin mixed sensitivity approach. The first technique uses a strategy based on the reformulation of the mixed-sensitivity design problem, where the closed loop transfer function from the plant input to the plant output is penalized. The second technique combines the H_infin optimal control with the bilinear transformation. The effectiveness of the techniques is illustrated by designing power system stabilizers for a simple power system. Computer simulations show that these techniques are effective in improving the damping of the system.