1. Distance Relay Specification
WECC TSS
January 23,2014
Amos Ang

2. Agenda
Purpose
Background
Relay Model Specification
Next Steps

3. 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

4. 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

5. 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

6. Distance Relay Specification

7. 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

8. 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

9. 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

10. 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

11. Blinders Sub-Model
Ability to shape the zone shape

12. 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

13. 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

14. Any Questions?