Distance Relay Specification WECC TSS January 23,2014 Amos Ang

Agenda Purpose Background Relay Model Specification Next Steps

Purpose To get approval from TSS for model specification To model relay behavior in powerflow and transient stability analysis To model interactions between RAS / SPS and Protection relays To facilitate transfer of information from System Protection to Transmission Planner Established a phased approach to implementing more functionality To satisfy the new TPL standards of modeling the actions of protection relays for compliance

Background Started with September 8th blackout Identified three zone distance relays that actuated Modeling SPS and Relays Ad-Hoc Task Force (MSRATF) was formed to gather all subject matter experts to work on the recommendations from Sept. 8th event One of MSRATF sub group was tasked to deal with relays Members of the sub group included input from Planning and Protection engineers Received MV&WG Approval in December 2013

Existing Relay Models ZLIN1 PSLF No transfer trip capability; No load encroachment function; No blinders DISTR1 PSSE Transfer trip capability, but requires input parameters for both end of line if no transfer trip; No load encroachment function; Limited blinder functionality; no out of step functionality ZPOTT 2 zones of protection; Assumes transfer trip; No load encroachment function; No blinders

Distance Relay Specification

Main Components of the Relay Generic Distance Relay Main Model Zone Detection Sub-Model Load Encroachment Sub-Model Blinders Sub-Model Transfer Trip Scheme Sub-Model

Generic Distance Relay Main Model There are four main functions of the main model Perform the logic needed from the outputs of the other sub-models Which elements to trip (up to 5 elements) Perform the reclosing scheme if it is available Houses the timings for all the zones

Zone Detection Sub-Model There are 4 zones that can be defined per distance relay main model Units are in Primary Ohms 6 different zone shapes to cover most of what is available to the Protection Engineer Lens Shape Circle Shape Tomato Shape Rectangular Shape Reactance Distance Impedance Distance Ability to perform logical operations up to 3 different shapes

Load Encroachment Sub-Model Function is to prevent relay from operating when load current comes into the detection zone Units are in Primary Ohms and degrees

Blinders Sub-Model Ability to shape the zone shape

Transfer Trip Scheme Sub-model Transfer Trip is the term of how the relay would trip the other side of the line This model specification starts with the simplest of them all which is the step distance transfer trip scheme – once it detects and “times out” then it trips the elements defined in the main model Building upon this sub-model would enable the Transmission Planner to have the correct timings of which breakers opens first and how much delay

Next Steps Phase 2 Develop ways to translate the relay settings to the powerflow / stability programs (automated?) More zone shapes (if needed) Out of step blocking / tripping functionality Pseudo Code for Transfer Trip Scheme and Reclosing Scheme (adopt and modify the SPS / RAS language being developed) Stock transfer trip schemes Stock reclosing schemes More reclosing schemes (as needed) Ability to select what part of the relay “failed” More than 3 tap lines – checking impedance input Phase 3 Modeling in the unbalanced phase environment

Any Questions?