The present invention provides control systems and methods for a power inverter. For example, a control system comprises a plurality of sensors and a controller. The plurality of sensors are configured to measure electrical signals that are indicative of output voltages and output currents of the power inverter. The controller, coupled to the power inverter, is configured to: determine a target power based on real power frequency droop information and a first frequency if the power inverter is in a voltage source mode; determine a target power based on a power limit and a predetermined power command if the power inverter is in a current source mode; and generate a second frequency based on the target power, a measured power, and a latency estimate of a simulated generator. The second frequency is used to control the output power of the power inverter.