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Directional Overcurrent Relay Specification. WECC TSS January 23,2013 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
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Directional Overcurrent Relay Specification WECC TSS January 23,2013 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 • To satisfy the new TPL standards of modeling the actions of protection relays for compliance
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
Relay Model Specification • Directional Sub-Model • Load Encroachment Sub-Model
Directional Element Sub-Model • The directional element is defined by its characteristic angle shown in the figure
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
Load Encroachment Sub-Model • Function is to prevent relay from operating when load current comes into the detection zone
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
Next Steps • Phase 2 • Modeling in the unbalanced phase environment