{
  "$schema": "https://ps-wiki.github.io/schema/v1/term.schema.json",
  "id": "transient-stability-assessment",
  "title": "Transient Stability Assessment",
  "description": "TSA. Monitor and determine transient stability of the system.",
  "language": "en",
  "tags": [
    "stability",
    "software",
    "system-operator",
    "pjm",
    "european-union",
    "europe"
  ],
  "related": [
    "transient-stability",
    "dynamic-stability"
  ],
  "breaking": false,
  "dates": {
    "created": "2025-03-15",
    "last_modified": "2025-12-03"
  },
  "authors": [
    {
      "name": "Jinning Wang",
      "url": "https://jinningwang.github.io"
    }
  ],
  "content": {
    "sections": [
      {
        "order": 1,
        "id": "definition-by-pjm",
        "title": "Definition by PJM",
        "type": "definition",
        "source_keys": [
          "pjm2024m3v67"
        ],
        "page": "p61, Revision 67",
        "body_md": "> In addition to the special operating procedures addressing stability limit issues in Manual-03B, PJM utilizes a real-time Transient Stability Assessment (TSA) tool.\n> TSA can monitor and determine transient stability of the system subject to **a select set of EMS contingencies** for balanced and unbalanced faults.\n> PJM models a select set of three-phase faults with normal clearing and single-phase faults with delayed clearing.\n> The contingencies or faults are in alignment with most planning events as defined in TPL-001-4 categories P1 through P4.\n>\n> TSA will also monitor and control for dynamic stability using a 3% damping criteria for the RTO.\n> TSA will display contingencies and impacted generators not meeting 3% damping criteria for units 10 MVA or above, as simulated between 10 and 15 seconds.\n> PJM will perform additional simulations to validate damping results not meeting criteria in Real-time.\n>\n> TSA is also utilized to assess transient voltage response.\n> The transient voltage criteria is recovery to a minimum of 0.7 p.u after 2.5 seconds (0.7 p.u. of nominal voltage).\n> Refer to Manual-37: Reliability Coordination for additional information.\n> The typical controlling actions for transient voltage exceedance are switching of static reactive devices, such as capacitor and reactors, to maintain a strong pre-contingency voltage profile and reserving dynamic reactive output from SVCs, STATCOMs, and generators, for post-contingency voltage support.\n>\n> TSA computes stability limits by using real time network models.\n> It **interfaces** with the [EMS](/wiki/real-time-reliability-model) and uses the State Estimation solution.\n> Other input data includes the dynamic model for over 3000 generators and fault clearing times for specific equipment.\n> For equipment without a specific fault clearing time, TSA will use zonal default clearing times.\n> TSA also calculates and provides recommended stability control measures to prevent generator instability.\n> Typically, the **control measure is expressed in terms of generator-specific MW adjustment**.\n> In some cases, a Mvar adjustment may resolve a stability issue.\n>\n> TSA is used to monitor and control the generators with known stability concerns as defined in PJM Manual-03B.\n> Since TSA uses real-time system conditions to assess stability, the limits tend to be less conservative or less restrictive than the manual operational procedures.\n> The operational procedure limits are usually determined using conservative assumptions in order to cover a wider range of operating conditions.\n> For scheduled transmission outages, TSA studies are used to determine the stability limits.\n> For forced outages, the Manual-03B operational procedure limits are used until a real-time TSA run is completed.\n> PJM will also use the Manual-03B operational procedure stability limits in certain cases, such as when TSA is down.\n"
      },
      {
        "order": 2,
        "id": "definition-in-a-european-union-regulation",
        "title": "Definition in a European Union Regulation",
        "type": "definition",
        "source_keys": [
          "eu2017guideline"
        ],
        "page": "p6",
        "body_md": "> ‘dynamic stability assessment’ means the operational security assessment in terms of dynamic stability;\n"
      }
    ]
  }
}