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Example: How to merge multiple PSS®E plant models into a network model

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Example version: v2

Software required:

PSS®E
Preview of example's gridmo Flow showing Nodes

Background​

Utilities and system operators create and maintain models of their electrical network which accurately represent existing network behaviour. These network models are often created using PSS®E, supporting systems which take snapshots of real-world operating conditions and manual 'massaging' to ensure case stability. These network models can then be made available to proponents (e.g. AEMO | Policy on provision of network data).

However, utilities may may only provide a model which is an accurate representation of existing behaviour. If you want to create a network model which represents future behaviour, you may need to modify the existing network model with known upcoming network augmentations (e.g. new generating systems which are under constructions and will soon be online, new transmission line, line growth/decline).

This example shows how you can augment a network model by merging multiple future plant models and redispatching the network model. The post-augmentation network model can then be used in other grid code studies (e.g. NER Chapter 5 Typical Generator Performance Standards (GPS)) to investigate the impact of a proposed generator.

For clarity, this example involves merging and dispatching generators which are already committed and which are not your proposed generator.

Merging plant models and adjusting dispatch​

In this example, we have a network model which represents existing network behaviour at winter peak load. We would like to create a network model which represents the network 12 months in the future when the winter peak load is approximately the same but two new solar farms have finished construction and are operating. These two new solar farms are the following:

  • Project 1 | Rated maximum active power = 20 MW | Forecast winter dispatch = 10 MW
  • Project 2 | Rated maximum active power = 40 MW | Forecast winter dispatch = 20 MW

In this example network, there is negligable net load growth and there is a market dispatch mechanism. Therefore, the addition of this new solar generation will displace generation from other neighbouring generation sources. When deciding which generators to dial down to accomodate the new generation, you want to choose the generators which would most likely be dialed in the real-world. Depending on the type of network, factors in this decision may include:

  • Energy market bid prices (i.e. higher priced bids are displaces by lower price bids)
  • Local constraints and curtailment
  • Planned decommissioning/maintenance

Merge project 1 model​

projects merged into network

Merge project 1 model in PSS®E Static Node using gridmo's "Merge into network" feature.​

model merge feature

Control the dispatch of the newly merged project​

set dispatch
tip

To choose an appropriate dispatch level of your merged model, you may wish to look at the generation levels of plants in the surrounding part of the network.

Redispatch neighbouring generators to maintain overall generation level in the network​

reduce network dispatch
tip

When deciding which generators to dial down, you could consider the following:

  • The location of the generator relative to the merged model (e.g. reducing generation in a different region to your merged model may significantly affect interconnector flows and/or the scenario being studied).
  • The average market price of the electricity generated by type of generator (e.g. batteries may generally be more expensive than solar or wind). It is reasonable to expect that a generator providing cheaper electricity will displace a more expensive generator.

Merge project 2 model​

projects merged into network

Same concepts as above with one addition:

Re-dispatch all previously merged projects​

The more SMIB models you merge into the network case, the more inaccurate their dispatch will be from the PSS®E Static Node which dispatched them (as each subsequent merged model will affect the load flow slightly). To ensure the dispatch matches the desired output, it is good practice to re-dispatch all previously merged SMIB models in the final PSS®E Static Node in your Run.

redispatch all merged models
note

After launching the Run and completing the simulation, you can extract the updated network case by navigating to the all-temp folder in the Outputs folder for this simulation. Within the all-temp folder for the PSS®E Dynamic Node, it will contain the updated .sav case named converged_case.sav.

Revision history​

Version 3 | 12 October 2025​

Improvements
  • Added subplots in Plot Node 1059 to show voltage and frequency at network buses 34502, 6604 and 6606.
  • Updated example to merge a 20 MW solar farm and a 10 MW solar farm, but not the 175 MW solar farm model.
  • Removed the Loop: Start Node which defined network faults. Simplified the example to only demonstrate a flat run.
  • Removed all subplots for 175 MW solar farm model.

Version 2 (v1.4.15.6) | 23 July 2024​

  • Updated Sticky Node helper text in example.

Version 1 (v1.4.15) | 20 June 2024​

  • First release of example file.