A microsource is provided, which includes a generator, a prime mover, and a controller. The prime mover includes a shaft connected to drive the generator to generate power at a frequency controlled by a rotation rate of the shaft. The controller calculates an operating frequency for the generator based on a comparison between a power set point and a measured power flow. A requested shaft speed for the prime mover is calculated by combining a maximum frequency change, a minimum frequency change, and the calculated operating frequency. A shaft speed adjustment is calculated for the prime mover based on a comparison between the requested shaft speed and a measured shaft speed of the prime mover. A fuel command for the prime mover is calculated based on the shaft speed adjustment. A rotation rate of the shaft of the prime mover is adjusted based on the calculated fuel command to control the frequency.