Abstract: Devices and methods for monitoring and determining alternating current (AC) power system parameters are provided. In some implementations, the device can include a processor; and at least one non-transitory computer-readable medium storing computer-executable instructions for implementing a number of components. The components include a monitor configured to: sense an AC line voltage signal and an AC current voltage signal; filter the AC line voltage signal; calculate average AC line voltage and current values based, at least, on a DC voltage and current values corresponding to the AC line voltage and current signals, respectively; determine fundamental AC line voltage and current signals based, at least, on zero crossings of the respective average AC line voltage value and the average AC line current value; and determine one or more AC power system parameters based, at least, on the fundamental AC line voltage signal and the fundamental AC line current signal.