Model-reference Adaptive Voltage Regulators

Abstract

This chapter illustrates the design of nodal voltage regulators using modelreference adaptive control theory for the discrete-time linear model presented in Chapter 3. Both indirect and direct methods are illustrated. As in the case of self-tuning voltage regulator design developed in Chapter 4, indirect model-reference adaptive design is articulated in two steps. In the first step, the parameters of the power system model are estimated recursively using a recursive least-squares algorithm with forgetting factor. In the second step the estimated parameters are then used to solve a Diophantine equation in the unknown polynomials regulator.

Conversely, in direct model-reference adaptive design, assuming a known operating point of the power system, the regulator parameters are determined by solving a model-reference design. Adaptive laws to update the regulator parameters are then designed using a normalized gradient method based on a standard quadratic cost function.

This chapter ends with a robustness analysis carried out with reference to a no-load voltage disturbance.