1. A method for detecting a possible cyber attack on an alternating-current power distribution grid, wherein the alternating-current power distribution grid excluding high voltage transmission lines, and the alternating-current power distribution grid having a plurality of remotely-operable elements, each remotely-operable element having a present state, the method comprising the following steps: periodically obtaining a first set of information about the present state of each remotely-operable element through a communication network or from instructions sent to the each remotely-operable element through a communication network, or both; employing the first set of information obtained about the present state of each remotely-operable element to prepare a first state estimation of the alternating current power distribution grid; periodically, but contemporaneously with obtaining the first set of information employed to prepare the first state estimation, making a plurality of micro-synchrophasor measurements at not less than two locations on the alternating current power distribution grid, wherein the micro-synchrophasor measurements being made with an angular resolution of ±0.015° or better; using the micro-synchrophasor measurements to calculate a plurality of synchrophasor parameter values; using the synchrophasor parameter values to calculate a second state estimation of the alternating current power distribution grid, wherein the second state estimation being contemporaneous with the first state estimation; comparing the first state estimation to the second state estimation, and detecting a possible cyber attack if the first state estimation and the contemporaneous second state estimation are not equal.