Measurement of the frequency dependent impedance of major station equipment

High-voltage direct-current (HVDC) converter stations generate radio frequency (RF) electromagnetic (EM) noise due to valve firing. The noise propagates into the AC and DC switchyards and along their corresponding transmission lines. This noise can affect the performance of adjacent communication, control, and computer equipment, and it can interfere with carrier system operation. Therefore, it is important to measure, predict, and mitigate the EM noise and interference. Measurements on equipment are necessary for the purpose of determining these impedance characteristics. A description is given of the instrumentation, improved measurement procedures, a systematic measurement program, and equipment representation concepts. All these have been developed and applied successfully in practice in the course of a project sponsored by the Electric Power Research Institute (EPRI). Transformer-related examples are used to illustrate the more relevant features of the study