Power quality refers to the degree to which the voltage, frequency, and waveform of a power supply system conform to established specifications. Good power quality can be defined as a steady supply voltage that stays within the prescribed range, steady AC frequency close to the rated value, and smooth voltage curve waveform (which resembles a sine wave) . In general, power quality is the compatibility between what comes out of an electric outlet and the load that is plugged into it. Power quality is important because any deviation from the expected levels of power quality can cause negative consequences such as equipment damage or malfunction, system shutdown, and data loss. Poor power quality can also lead to lower operational efficiency and higher maintenance costs. Power quality is often measured based on standards, which serve as guidelines for measuring and evaluating the quality of the electrical power supply. Some examples of international standards for power quality include IEC 61000-4-30.