Directional Overcurrent Relay Specification WECC TSS January 23

Directional Overcurrent Relay Specification WECC TSS January 23, 2013 Amos Ang TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 1

Agenda § Purpose § Background § Relay Model Specification § Next Steps TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 2

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 § To satisfy the new TPL standards of modeling the actions of protection relays for compliance TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 3

Background § Non-directional overcurrent relays were approved in a previous TSS meeting § M&VWG approved the specifications in December 2013 § Increasing the functionality of the models that we have, then we can model the functions of these relays more precisely TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 4

Relay Model Specification § Directional Sub-Model § Load Encroachment Sub-Model TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 5

Directional Element Sub-Model § The directional element is defined by its characteristic angle shown in the figure TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 6

Consideration for Electro-Mechanical Relays § Electro-mechanical relays do not have a setting to enter a characteristic angle § The way to translate the settings to the characteristic angle – Determine the angle between voltage and current at unity power factor for the relay connection used – Determine the angle that the current must shift to achieve maximum torque, normally this angle will be lagging the unity power factor – The angular shift in a lagging direction from unity power factor to maximum torque is the characteristic angle or angle of maximum torque on the R-X diagram TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 7

Load Encroachment Sub-Model § Function is to prevent relay from operating when load current comes into the detection zone TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 8

Modification to Existing Overcurrent Relay Models § To implement the directionality and/or load encroachment functionality to the existing overcurrent relays – Add the function of torque control which activates the overcurrent relay’s tripping function including the timer function after the direction and load encroachment have been evaluated TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 9

Next Steps § Phase 2 – Modeling in the unbalanced phase environment TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 10

Any Questions? TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 11