Project 2–Security Region for Grid Operations

Problem and Approach:

Consider a two-area power system. The base-case powerflow and dynamic data in PSS/E format will be provided.

Consider 10 seconds time domain simulations for three critical contingencies:

  • Contingency #1: Three-phase fault happens on one line between buses 6 and 7 next to bus 6; after 5 cycles, it is cleared by tripping that line.
  • Contingency #2: Three-phase fault happens on one line between buses 8 and 9 next to bus 9; after 5 cycles, it is cleared by tripping that line after 5 cycles.
  • Contingency #2: Three-phase fault happens on one line between buses 8 and 9 next to bus 9; after 5 cycles, it is cleared by tripping that line plus an additional line between buses 8 and 9.

Based on the base-case power flow data, create new operating points by increasing the loads at Bus 7 and Bus 9 (denoted by PL7 and PL9, respectively)and accordingly the output of generator G3 (denoted by PG3). The outputs of the other generators are fixed. Determine the security region for the system about PL7 and PG3 (PL9 as a relaxation variable). The security region is defined as the set of operating points without violation of the following criteria

  • Static security criteria:
  • Generation limits: outputs of all generators are within their limits
  • Line thermal limits: MW flows of all lines are lower than the line thermal limits
  • Dynamic security criteria: for 10 seconds following a given contingency
  • Angle stability:the system has positive stability margin (use the definition in Project #1 or 360o as the limit for largest angle distance)
  • Transient voltage: the maximal voltage drop duration (TVdrop) below the Voltage Drop Threshold of 0.7pu is shorter than 20 cycles.
  • Small-signal: Oscillations are damped (decreasing swings)

As illustrated in the figure below, present the security region in the PL7-PG3 plane by appropriate visualization approaches, e.g.

  • All criteria about one contingency.
  • One or more criteria for all contingencies

Deliverables:

  • Project presentation on 4/24
  • A no more than 6 pages report by 5/1. Use the IEEE paper template at

Hints:

  • An approach could be: (1) Place a number of points in the PG3-PL7 plane; (2) Create an operating condition matching each point (by adjusting power flows of the base case); (3) Simulate contingencies at each operating condition; (4) Determine the boundary of a region where no violation occurs.
  • You may use either PSS/E or Powertech’s TSAT software to do simulations. TSAT software is able to automatically search security limits in one dimension (with a source and a sink defined).