Power quality analysis and suppression of conducted emissions on power grids

Electric vehicles provide an environmentally friendly solution by reducing dependence on fossil fuels. Vehicle-to-grid and grid-to-vehicle technology makes it possible for electric vehicles to supply or take energy from the grid through energy storage systems. The use of bidirectional AC/DC converters for this purpose is becoming increasingly common in the grid. In addition, the number of power converters is increasing as renewable energy sources are connected to the grid. DC power sources can be converted directly to AC with an inverter, or they can be pre-set to an inverter-compatible DC voltage level using a DC-DC converter and then converted to three-phase using an inverter. Advances in power electronics and semiconductor technologies have enabled electrical and electronic device designs to increase switching capability at high frequencies, resulting in compact designs with high efficiency and power density. However, increased switching frequency brings with it the problem of electromagnetic interference. This interference can often adversely affect or damage the operation of converters and other equipment connected to microgrids. While there are standards and norms for frequencies up to 2 kHz and starting from 150 kHz, in the frequency range 2-150 kHz there are only recommended methods and radiation limits. Therefore, it is necessary to find new methods for frequencies in this range or to adapt methods for other frequency ranges. Taking into account the electromagnetic interference of the device at the initial design stage can also enable designers to meet electromagnetic compatibility at low cost before realization. In this study, conducted emission measurements were performed on both DC and AC single-phase/three-phase systems, utilizing commonly employed inverter types. Since there is no standard for the frequency range 9-150 kHz, standard limits are proposed for this range. The actual measurement results are compared with the simulation results and the results are found to be consistent with each other. Filter design steps are explained to reduce the radiation transmitted to the network. The measurement uncertainties are taken into account while calculating the filter design parameters and the filter design steps are explained to meet the worst case conditions and the noise attenuation performance is verified experimentally and simulated. The obtained results are presented with a statistical approach and a comparative evaluation is made.