DIGITAL FILTER PROCESSING UNIT, DIGITAL PROTECTION RELAY DEVICE AND DIGITAL DIFFERENTIAL RELAY DEVICE

摘要

PURPOSE:To attain fast discrimination of relay operation with high accuracy by obtaining an input data required for the calculation of a protection relay at a frequency (density) being N times the sampling frequency and constituting a protection relay device through the use of the processing unit of such data. CONSTITUTION:An input data representing the state variable such as an inputted voltage or current is subjected to A/D conversion (4) for each sampling period Ts. Then filter processing by digital filter calculation is applied. The filter processing is repeated based on the preset filter coefficient for a period TF being 1/N of the sampling period Ts and it is possible to offer the input data required for the calculation of the protection relay at a frequency higher than the sampling frequency thereby attaining high speed operation discrimination and highly accurate operation of the protection relay. Furthermore, the frequency characteristic in the filter calculation operation is a characteristic passing the fundamental wave frequency component of the input data while eliminating a high frequency, and even if filter processing is applied to a simulated input data in place of a true input data, the fundamental wave data equal to the processing of sampling substantially at a short pitch of the frequency being a multiple of N is obtained.