Table Of Content

MICOM P437 Distance Protection Version -307 –408+409 –611 Upgrade Documentation P437/EN AD/AB7 (AFSV.12.09960 EN) (Issue A) In the new version of P437 several new features and changes on existing features have been added. These are described with reference to the documentation listed below. References Release Version Documentation 26.02.2006 P437-307-408/409-610 Manual P437_EN_M_Ba7 (AFSV.12.09910) P437 Upgrade Documentation (continued) 1 Overview Version Changes P437-307-408/409-611 Hardware No changes Release: 28.02.2007 Diagram No changes Software IEC Enhancements of protocol implementation: GOOSE (cid:133) 2nd SNTP server GSSE (cid:133) VLAN priority COMM1 Bug fixing: The following spontaneous messages were missing: 034.047 MAIN Manual trip signal A 034.048 MAIN Manual trip signal B 034.049 MAIN Manual trip signal C DIST Improved measuring logic to provide fast 3-pole tripping in case of phase-phase-ground faults, with one phase-ground loop impedance getting significantly slower into zone 1. The underimpedance starting logic has been improved to pick up faster in case of faults with almost no change in current magnitude. The directional characteristic is now settable. PSB Separate counters for number of stable swings as well as number of pole slips have been implemented. These counters are accomplished by settable levels at which binary signals are raised that could be used for tripping purposes. Bug fixing: (cid:133) The ∆Z detection did not operate in all cases, if the apparent impedance moved “from the left to the right” into the power swing detection zone. (cid:133) The maximum blocking timer was not correctly re-triggered each time when entering the power swing detection zone. Thus it could by chance time out during a consecutive power swing cycle. SOTF The SOTF dead line detection logic could now be enabled or disabled. PSIG Weak-Infeed Logic blocking feature has been modified to provide pole- selective blocking by CB auxiliary contact information (52a inputs). The scheme logic has been enhanced to cope 3-ended line applications. The distance dependent send logic has been modified for improved operation in case of 2pG faults: If fault direction signals forward and backward are present at the same time, the send signal is based on the selective Z1 decision only (not on Z1e). Bug fixing: In distance-dependent blocking scheme, the PSIG tripping time was not started, if the zone timing setting was 001.236 DIST Zone timer start = ‘With zone starting’. U-4 P437/EN AD/Ab7 // AFSV.12.09960 EN /// P437-307-408/409-611 P437 Upgrade Documentation (continued) Version Changes ARC Zone 1 extension tripping during reclosing is now executed from ARC, even if PSIG is in operation. The duration of the zone extension is as long as the set reclose command (015.067 MAIN Close cmd.pulse time), ifen if the reclose command is stopped because of the close-signal from the CB (015.042 MAIN RC inhib.by CB close = ‘Yes’). ASC The selection of voltage control conditions (operating modes) has been enlarged by an exclusive-OR condition, i.e. (re-)closing is enabled, if exactly one side is “dead” while the other side must be “live” (setting abbreviated “N V&Vref or V&n Vref” means “(NOT V AND Vref) OR (V AND NOT Vref)”). In operating mode “Vref & Z1 but not V” the meaning of Z1 has been changed to “DIST zone Z1 trip OR protective signaling Z1e trip”, so reclosure is possible if the primary fault is on the line. GFSC The user settable blocking condition of the function has been changed to an m-out-of-n selection, using the same enlarged list as for GSCSG. Consequentially, the previous setting 002.137 GFSC: Block. w. DIST start is removed. For ground faults with small neutral displacement voltage an optional ‘virtual current polarisation’ has been implemented. This feature uses a faulty phase selector, which is based on the measured change of phase currents. Along with the signaling scheme (GSCSG) the priority of the function has been changed to provide faster 1-pole trips. GSCSG The selection list for user defined blocking conditions (002.180 GSCSG: Fct.assign. blocking) has been further expanded by internal trip decisions as well as parallel and transfer trip signals. The tripping timer is now started from 039.088 GFSC IN> triggered signal only. Transient blocking timer is now always started upon reset of a GSCSG backward direction decision. P<> Directional power protection function is now available. U-5 P437/EN AD/Ab7 // AFSV.12.09960 EN /// P437-307-408/409-611 P437 Upgrade Documentation (continued) 2 Functional Details 2.1 Distance Protection (Function Group DIST) Based on recent RTDS (Real Time Digital Simulator) simulated type test cases, distance protection operation for specific conditions has been improved. Distance decision for 2pG-faults To provide correct operation for cross-country faults or inter-system faults on double circuit lines (2pGG faults), it is mandatory to evaluate only the both phase-ground loop impedances. This is possible by setting, yet during tests this setting resulted in staggered tripping for very close 2pG faults, because one PG loop impedance could appear in backward direction. The reason for this is that the impedance is calculated by using the ground factor k of the line, yet as no line impedance is involved in the G measuring loop any more and as the source ground factor was significantly smaller than the line factor, thus one PG loop impedance is “misleading”. With version –611 the following solution is implemented: If starting identifies a 2pG fault condition, and “PG loops” evaluation is selected, than the phase-phase voltage is used to determine whether it is a close fault, which is the case ir V < 10% V . In this case, the PG-loop impedances (for the distance and directional PP nom measurement) are calculated with k = 0; otherwise normal equation with set k is used. G G Additionally to the 2 PG impedances the PP impedance is calculated, too, to secure simultaneous 3-pole tripping, because it could happen that the 2 PG impedances settle in zone 1 (or Z1e) with different “speed” – just depending on the fault transients. Always all 3 impedances (e.g. BN, CN and BC for a BCN fault) are calculated, and the zone decisions are then compared: 1) If both PG impedances are in zone 1, P437 immediately trips 3-pole. 2) If one PG and the PP impedance are in zone 1 and the 2nd PG loop is in forward direction, then P437 trips 3-pole, too. Taking care for the directional decision acertains, that – just in case of cross-country and intersystem faults (2pGG faults) – both PG faults are on the protected line. The zone 1 decision of the PP loop then is sufficient to secure that both faults are in zone 1, too. In applications with parallel lines, during intersystem faults one PG fault could be on the parallel line, but then either its direction is backwards or the PP loop impedance is outside zone 1. 3) If after the first calculation loop just one zone 1 decision is determined, than the DIST processing task duration is prolonged and all 3 impedances are calculated again. This is done to make shure that normal 2pG faults are immediately tripped 3-pole and the risk of staggered tripping is minimized. The disadvantage is that for parallel line applications in case of cross- country/intersystem faults the correct 1pole trip could be delayed by up to ~7 ms. So in order to get a proper balance of speed and correct 1p/3p trip decision, this measuring repitition is only done once. U-6 P437/EN AD/Ab7 // AFSV.12.09960 EN /// P437-307-408/409-611 P437 Upgrade Documentation (continued) 1pG starting during 2pG faults In some cases a fast 1pG starting was observed during a 2pG fault. This incomplete fault type determination also forced an initial 1-pole trip. During the 2nd processing cycle the correct type of fault was identified and 3-pole trip was issued, thus a unfortunate staggered tripping took place. To solve this problem, the starting conditions are now checked again during the first distance measuring cycle. Settable directional characteristic In some cases with external phase-phase faults with a high intermediate infeed at the remote busbar, the apparent directional angle (calculated from memorised voltage and fault current) appeared at about –40°...-70°, i.e close to the directional line, sometimes even in the forward section. This resulted from a severe phase shift of V voltage upon AB fault inception. The solution implemented for this condition is a settable directional characteristic angle as figure below. Figure 1 New settable distance directional characteristic U-7 P437/EN AD/Ab7 // AFSV.12.09960 EN /// P437-307-408/409-611 P437 Upgrade Documentation (continued) 2.2 Power Swing Blocking (Function Group PSB) New counters Two new counters are implemented to count stable and unstable swings: (cid:133) 006.025 PSB No. stab. PSwing This counter is incremented after each stable power swing cycle, i.e. if the positive sequence impedance leaves the power swing detection polygon on the same side as it entered (equal signs of resistive component R ) pos (cid:133) 006.026 PSB No. OOS This counter is incremented after each unstable power swing cycle (= upon out-of-step condition), i.e. if the positive sequence impedance leaves the power swing detection polygon on the opposite side as it entered (unequal signs of resistive component R ) pos Counter reset timer Upon each incrementing the counter, a dedicated timer stage is triggered. If this timer elapses while no further incrementing of the same counter takes place, then it is supposed that the power swing condition has stopped and this counter gets reset to 0. For this timer stage the existing setting 014.055 PSB Max. blocking time is used, which is already recommended to be set to the anticipated maximum power swing cycle time. Counter comparators For each counter comparative thresholds are provided: (cid:133) 006.027 PSB Perm. no. stab. PS [setting range 1 ... 10 / blocked] is the number of stable power swings, after which the signal 006.030 PSB Perm. no. PS reach is raised (cid:133) 006.028 PSB Perm. no. OOS [setting range 1 ... 10 / blocked] is the number of unstable power swings, after which the signal 006.035 PSB Perm. no. OOS reach is raised These binary signals remain active (value “Yes”) until their associated counter resets. They are freely configurable to any physical output relays, LED’s and communication outputs (InterMiCOM, GOOSE, GSSE). They are logged in fault recording and – depending on the communication protocol and signal mapping – messaged through the information communication interfaces (COMM1). Also these signals can be directly linked into the general trip command, e.g. to provide delayed tripping if a power swing does not get removed in due time by the generator control equipment. U-8 P437/EN AD/Ab7 // AFSV.12.09960 EN /// P437-307-408/409-611 P437 Upgrade Documentation (continued) 2.3 Switch on to Fault Protection (Function Group SOTF) Dead line detector The dead line detection logic implemented in version -610 was not useful, as SOTF protection remained operative as long as the CB was signaled in 3-pole open condition, even if the line was already energized (from remote CB or from local 2nd CB in 1½ CB schemes. Therefore the CB status input is no longer taken into consideration. On the other hand, in few cases CT failures occurred from picking up load current. For such cases it is not desirable to inhibit SOTF, even if the line is already energized. To take care for this condition, too, the dead line inhibit logic can now be enabled or disabled by setting. Figure 2 Decision 'Line dead' in the 'Switch on to fault protection' function Note: Internal signal name ‘Dead line’ remained unchanged to as it is required in figure 3-129 in the referenced full manual. U-9 P437/EN AD/Ab7 // AFSV.12.09960 EN /// P437-307-408/409-611 P437 Upgrade Documentation (continued) 2.4 Protective Signaling (Function Group PSIG) Refinement of Weak-Infeed blocking logic The weak-infeed blocking logic has been modified so that phase-selective blocking is raised upon the CB pole open condition. Figure 3 Phase-selective blocking of the weak infeed logic (replaces fig. 3-165 of the referenced manual) U-10 P437/EN AD/Ab7 // AFSV.12.09960 EN /// P437-307-408/409-611