GE Multilin C70 Capacitor Bank Protection and Control System 2-152 PRODUCT DESCRIPTION 2.3 SIGNAL PROCESSING22.3SIGNAL PROCESSING 2.3.1 UR SIGNAL PROCESSINGThe UR series relays are microprocessor-based protective relays that are designed to measure power system conditionsdirectly via CT and PT inputs and via other sources of information, such as analog inputs, communications inputs and con-tact inputs. The following figure shows the overall signal processing in URs.An analog low pass anti-aliasing filter with a 3 dB corner frequency is set at 2.4 kHz and is used for current and voltageanalog filtering as well as signal conditioning. The same filtering is applied for phase, ground currents, phase-to-phase(when applicable), and auxiliary voltages. The 2.4 kHz cut-off frequency applies to both 50 Hz and 60 Hz applications andfixed in the hardware, and thus is not dependent on the system nominal frequency setting.Figure 2–3: UR SIGNAL PROCESSINGThe UR samples its AC signals at 64 samples per cycle, that is, at 3840 Hz in 60 Hz systems, and 3200 Hz in 50 Hz sys-tems. The sampling rate is dynamically adjusted to the actual system frequency by an accurate and fast frequency trackingsystem.The A/D converter has the following ranges of AC signals:Voltages:(EQ 2.1)Currents:FromCT/VTUIAnalog Inputs Analog low-pass filterAnalog-to-DigitalConverterADigital band-pass filterDSP modulePhasorestimation½ cycleFourier1 cycleFourierRMSvaluesFundamental freq.Phasors,Seq. com-ponentsDSamplingfrequencyCPU moduleI>Z<U<ProtectionalgorithmsIRIG-BIEEE1588SNTPTrackingfrequencyselection,estimationAccurateReal-Timeclock SynchrophasorscalculationsSerialportsEthernetports Communi-cationprotocolsControlelements,monitoringelements,FlexLogic,Aggregation,post-filteringContact InputsmoduleHMIDdebouncefilteringOptoisolatedAnalog InputsmoduleDCmA, RTDADInter-relaycommsmoduleChannelmonitoringCRC checkG.703, RS-422,C37.94, direct fiberContact OutputsmoduleEthernet SerialPMU (IEEE C37.118,IEC 61850-90-5)IEC 61850 (GOOSE,MMS Server)DNP, Modbus,IEC60870Comtrade, dataloggerEventsInter-relaycommsmoduleFrequencyTAnalog OutputsmoduleTime stampingSynchro-phasorsfiltering859740A1.vsd2± 260 V( )⋅
