Yes when considering the generating source for grid connection. Power Quality guidelines specify in case of over voltage and under voltage ride through, the Generating Unit should be able to bring back the voltage level to the transmitting voltage level as it affects all the loads connected at the point where this GU is connected. This leads to failure or poor performance of the devices connected to this network on the load side. for low voltage ride through, when the voltage drops as low as 10% of the rated voltage, within a specified period of time about 0.6sec it should bring back the voltage to transmission level, if not this GU is automatically disconnected from the grid with economic losses to the supplier and possibly with lower supply for a higher load demand. This increases the power demand on other GU connected to this network. Voltages between 90% and 110% of the rated voltage should be compensated for with reactive power or they lead to flicker phenomenon. Over voltage higher than 110% are not studied so much in detail, or atleast I have no concrete information on that.