Three-phase measurement evaluation using a high-speed processorwith snapshot facility

A homogeneous measurement evaluation system is presented which provides all characteristic electrical parameters in a HV substation. It can be applied to asymmetric and to distorted power systems. Its application software consists of four parts for each function: preprocessing, frequency shift, filtering, and arithmetic functions. Its processor features the snapshot facility, i.e. all voltage and current phases of one feeder can be picked up simultaneously, thus eliminating interpolation errors. The accuracy of the evaluated parameters is Cl.0.2 and Cl.0.5 respectively, including RMS values of harmonics. Analog antialiasing filters are not required. Amplitude and phase errors of instrument transformers can be compensated. Since the applied processor is fast, real-time results are obtained which meet even the stringent requirements of static VAr compensators or other power electronics control equipment. An application for an EHV gas-insulated substation is described