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

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

TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 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 3

TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 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 4

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

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

TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 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 7

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

TRANSMISSION & INTERCONNECTION PLANNING T&D BUSINESS UNIT 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 9

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

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