ABB REC670 2.1 IEC Product Manual

Contents

ABB REC670 2.1 IEC Product Manual Manual pdf 25 page image

9. Secondary system supervisionCurrent circuit supervision CCSSPVC M12444-3 v10Open or short circuited current transformer cores can causeunwanted operation of many protection functions such asdifferential, earth-fault current and negative-sequence currentfunctions.Current circuit supervision (CCSSPVC) compares the residualcurrent from a three phase set of current transformer coreswith the neutral point current on a separate input taken fromanother set of cores on the current transformer.A detection of a difference indicates a fault in the circuit andis used as alarm or to block protection functions expected togive inadvertent tripping.Fuse failure supervision FUFSPVC SEMOD113820-4 v11The aim of the fuse failure supervision function FUFSPVC is toblock voltage measuring functions at failures in the secondarycircuits between the voltage transformer and the IED in orderto avoid inadvertent operations that otherwise might occur.The fuse failure supervision function basically has threedifferent detection methods, negative sequence and zerosequence based detection and an additional delta voltageand delta current detection.The negative sequence detection algorithm is recommendedfor IEDs used in isolated or high-impedance earthednetworks. It is based on the negative-sequence quantities.The zero sequence detection is recommended for IEDs usedin directly or low impedance earthed networks. It is based onthe zero sequence measuring quantities.The selection of different operation modes is possible by asetting parameter in order to take into account the particularearthing of the network.A criterion based on delta current and delta voltagemeasurements can be added to the fuse failure supervisionfunction in order to detect a three phase fuse failure, which inpractice is more associated with voltage transformerswitching during station operations.Fuse failure supervision VDSPVC GUID-6AF2219A-264F-4971-8D03-3B8A9D0CB284 v4Different protection functions within the protection IEDoperates on the basis of measured voltage at the relay point.Some example of protection functions are:• Distance protection function.• Undervoltage function.• Energisation function and voltage check for the weakinfeed logic.These functions can operate unintentionally, if a fault occursin the secondary circuits between voltage instrumenttransformers and the IED. These unintentional operations canbe prevented by VDSPVC.VDSPVC is designed to detect fuse failures or faults in voltagemeasurement circuit, based on phase wise comparison ofvoltages of main and pilot fused circuits. VDSPVC blockingoutput can be configured to block functions that need to beblocked in case of faults in the voltage circuit.Multipurpose filter SMAIHPAC GUID-EB0B11C3-FF79-4B8D-A335-649623E832F9 v2The multi-purpose filter function block, SMAIHPAC, isarranged as a three-phase filter. It has very much the sameuser interface (e.g. inputs and outputs) as the standard pre-processing function block SMAI. However the main differenceis that it can be used to extract any frequency componentfrom the input signal. Thus it can, for example, be used tobuild sub-synchronous resonance protection for synchronousgenerator.10. Scheme communicationScheme communication logic for distance or overcurrentprotection ZCPSCH M13860-3 v9To achieve instantaneous fault clearance for all line faults,scheme communication logic is provided. All types ofcommunication schemes for permissive underreaching,permissive overreaching, blocking, delta based blocking,unblocking and intertrip are available.The built-in communication module (LDCM) can be used forscheme communication signaling when included.Current reversal and weak-end infeed logic for distanceprotection ZCRWPSCH M13896-3 v14The ZCRWPSCH function provides the current reversal andweak end infeed logic functions that supplement the standardscheme communication logic. It is not suitable for standaloneuse as it requires inputs from the distance protectionfunctions and the scheme communications function includedwithin the terminal.On detection of a current reversal, the current reversal logicprovides an output to block the sending of the teleprotectionsignal to the remote end, and to block the permissive trippingat the local end. This blocking condition is maintained longenough to ensure that no unwanted operation will occur as aresult of the current reversal.On verification of a weak end infeed condition, the weak endinfeed logic provides an output for sending the receivedteleprotection signal back to the remote sending end andother output(s) for local tripping. For terminals equipped forsingle- and two-pole tripping, outputs for the faulted phase(s)are provided. Undervoltage detectors are used to detect thefaulted phase(s).Local acceleration logic ZCLCPSCH M13823-3 v6To achieve fast clearing of faults on the whole line, when nocommunication channel is available, local acceleration logicZCLCPSCH can be used. This logic enables fast fault clearing1MRK 511 361-BEN BBay control REC670 2.1 IECProduct version: 2.1ABB 25