Jeffy Mathew ECEN 679 Spring 2014

 Adaptive Relaying permits and seeks to make adjustments automatically in various protections in order to make them attuned to prevailing power system conditions. [3]  Important features ◦ Functions defined through software ◦ Have communication capability

 Current relay settings are calculated off-line  Desirable to change settings based on the dynamic variations in the system ◦ Frequency variation ◦ Fault resistance in SLG faults ◦ Power swings  Using local data, or local data exchange

 High SIR (Source Impedance Ratio) causes low fault voltage.  Cold Load Pickup ◦ Traditionally relays trip instantaneously followed by time delayed operation to override the inrush current.

 Adaptive Distance Protection Control System  Adaptive loop consists of identification, decision, and changes.

 Fault Detection and Measuring ◦ Fault Detection ◦ Fault Type Classification ◦ Fault Measurement  Adaptive Method for Change in Frequency  Adaptive Method for Single Line to Ground Fault Resistance  Adaptive Method for Power Swings in System ◦ Out-of-step relaying ◦ As power swing develops, relays can switch from tripping to blocking function

 Adaptive relaying helps to discriminate between 3-phase faults and power swings. ◦ It is possible to differentiate between a 3Φ fault and a power swing by looking for the presence of pre- filter group delay. ◦ Pre-filtering of signals allows for:  Removal of travelling wave noise  Removal of DC offsets

 Adaptive relay is capable of very high speed operation, maintaining a good reach point accuracy in the presence of travelling wave noise and is immune to the presence of harmonics or variation in power system frequency.

 Faster computation of settings  Automatic Reclosing settings can be adjusted ◦ Type and Severity of Fault ◦ Hard or Soft Circuit Breaker Operation ◦ Optimizing Circuit Breaker Wear  Faster protection, slower tripping time  Minimizes compromises between dependability and security ◦ Achieve increased dependability and security

 If relays change their settings themselves, there is a chance that the relays will not coordinate with each other properly.  Risk of Liability  Expensive to design  Chance that communication systems may fail ◦ Have to develop fallback position and safety checks

 Lecture Notes  Zhang Zhizhe and Chen Deshu, “An adaptive approach in digital distance protection”, IEEE Transactions on Power Delivery, Vol. 6, No. 1, January  Stanley H. Horowtiz and Arun G. Phadke, “Power System Relaying”. pg  Y.Q. Xia, K.K. Li, and A.K. David, “Adaptive Relay Setting for Stand-alone Digital Distance Protection”, IEEE Transactions on Power Delivery, Vol. 9, No. 1, January 1994

 Moore, P. J.; Johns, A.T., "Adaptive digital distance protection," Developments in Power Protection, 1989., Fourth International Conference on, vol., no., pp.187,191, Apr 1989 keywords: {digital simulation;microcomputer applications;power engineering computing;power system protection;relay protection;14 bit A/D converter;16 bit microprocessor;digital distance protection;digital distance relay;high-resistance earth faults;microprocessors;power swings;power systems;simulation studies;state-of-the-art}, URL: &arnumber=20639&isnumber=822http://ieeexplore.ieee.org/stamp/stamp.jsp?tp= &arnumber=20639&isnumber=822