Directional Elements – How Fast Can They Be? Armando Guzmán, Venkat Mynam, Veselin Skendzic, and Jean León Eternod, Schweitzer Engineering Laboratories, Inc. Rafael Martínez Morales, Comisión Federal de Electricidad

Directional Elements Are part of pilot protection schemes and can detect high-resistance faults when applied in permissive overreaching transfer trip (POTT) schemes Add security to distance elements Supervise overcurrent elements Use time-domain incremental-quantity (TD32) and traveling-wave (TW32) elements to allow faster operation

Incremental Quantities Provide Fault Information

Replica Current D𝑖𝑧 Simplifies Pure Fault Network Representation ∆𝑣=− 𝑅 𝑆 ∆𝑖+ 𝐿 𝑆 𝑑∆𝑖 𝑑𝑡 ∆𝑣=− 𝑍 𝑆 𝑅 𝑆 𝑍 𝑆 ∆𝑖+ 𝐿 𝑆 𝑍 𝑆 𝑑∆𝑖 𝑑𝑡 ∆ 𝑖 𝑍 = 1 𝑍 𝑆 𝑅 𝑆 ∆𝑖+ 𝐿 𝑆 𝑑∆𝑖 𝑑𝑡 Replica current: Even simpler equations… ∆𝑣=− 𝑍 𝑆 ∆ 𝑖 𝑍

Incremental Quantity Directional (TD32) Element Reverse fault: ∆𝑣= 𝑍 𝐿 +𝑍 𝑅 ∆𝑖 𝑍 Forward fault: ∆𝑣=− 𝑍 𝑆 ∆𝑖 𝑍

Operating Quantity Torque Like in Electromechanical Relays 𝑇 𝑂𝑃 =−∆𝑣∙∆ 𝑖 𝑍

Operating and Restraining Quantities 𝑇 𝑂𝑃_𝐹𝑊𝐷 = 𝑍 𝑆 ∙ ∆ 𝑖 𝑍 2 𝑇 𝑅𝑇_𝐹𝑊𝐷 =𝑇𝐷32𝑍𝐹∙ ∆ 𝑖 𝑍 2 𝑇 𝑅𝑇_𝑅𝑉𝑆 =−𝑇𝐷32𝑍𝑅∙ ∆ 𝑖 𝑍 2 𝑇 𝑂𝑃_𝑅𝑉𝑆 =− 𝑍 𝐿 + 𝑍 𝑅 ∙ ∆ 𝑖 𝑍 2

Loop Incremental Quantities Provide Directional Decision Voltage Current AG ΔvAG ΔiZAG = ΔiAZ – Δi0Z

TD32 Directional Element Response to Forward CG Fault

TD32 Provides Speed With Security Volts, Amps (Secondary) VA, Secondary Integrated VA

Birth of a Traveling Wave (TW) At Fault Location 408 kV Voltage Collapse vL – G t GROUND

Birth of a TW At Instant of Voltage Collapse 408 kV TW front emanates in both directions on faulted conductor Current waves are concurrently produced vF iF

TW Polarities as Seen by Relays Internal Fault (Forward Event)

TW Polarities as Seen by Relays External Fault

Use Differentiator Smoother Filter to Extract TW Signal CG Fault on 400 kV, 224 km Line Use Differentiator Smoother Filter to Extract TW Signal

Directional Decision Is Based On Integrated Torque TW32 element chooses phase associated with maximum integrated torque and its reported direction

CTs Faithfully Reproduce High-Frequency Signals Utilities have good experience with current TW-based fault-locating devices

CCVTs Provide First Wave Information PROT415_TravelingWaveProtection_r2 CCVTs Provide First Wave Information

TW32 Design Accommodates CCVT Performance

Fast and Secure POTT Scheme Local Terminal TD32 provides dependability and security Remote Terminal TW32 provides speed

CFE 400 kV Network Relays on MID-TMD Line SPT Application

Performance of TD32 and TW32 Elements Event Date Terminal Fault Type TW32 Operating Time (ms) TD32 Operating Time (ms) Jan. 7, 2017 MID Internal, AG 0.138 1.2 Jan. 15, 2017 TMD External reverse, AG - 1.7 External forward, AG 1.9 Jan. 16, 2017 External reverse, CG 1.8 Mar. 28, 2017 Internal, CG 0.106 1.39 May 4, 2017 0.105 1.1 0.094 1.06 Aug. 23, 2017 Internal, AG, High Rf 8.75 7.8

Directional Element Response to Forward CG Fault

TD32 Element Operates in <2 ms Integrated VA VA TD32 Element Operates in <2 ms

TW32 Element Operates in <150 µs PWRA PWRB PWRC VA TW32 Element Operates in <150 µs

Performance of TD32 and TW32 Elements Event Date Terminal Fault Type TW32 Operating Time (ms) TD32 Operating Time (ms) Jan. 7, 2017 MID Internal, AG 0.138 1.2 Jan. 15, 2017 TMD External reverse, AG - 1.7 External forward, AG 1.9 Jan. 16, 2017 External reverse, CG 1.8 Mar. 28, 2017 Internal, CG 0.106 1.39 May 4, 2017 0.105 1.1 0.094 1.06 Aug. 23, 2017 Internal, AG, High Rf 8.75 7.8

Directional Element Response to Reverse AG Fault

TD32R Element Operates in <2 ms VA TD32R Element Operates in <2 ms Integrated VA

CFE Field Evaluation POTT Scheme Based On TD32 and TW32 Elements 8 months, 9 fault records TD32 operates reliably for all faults Fastest operating time: 1.06 ms Average operating time: 2.97 ms TW32 detects 3 of 4 internal faults Average operating time: 116 μs Secure for all events and dependable for all faults (including high-resistance faults)

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