A digital excitation control system for use on brushless excited synchronous generators

Automatic voltage regulators for small to medium size brushless excited synchronous generators have traditionally utilized analog electronics. Modern voltage regulator systems are beginning to utilize the power, flexibility, and cost advantage of the microprocessor for control. Furthermore, digital voltage regulators have the added advantage of ease of compensator custom-design. This paper presents a new method for determining the stability parameters for small/medium size generators that have limited effect on overall system stability. A digital excitation control system (DECS) is used as a platform for this discussion. DECS utilizes a discrete proportional, integral and derivative (PID) control algorithm. A direct design (pole placement) method for selecting PID parameters is presented along with the test results.