# Simplex Nodal

> Learn electricity markets and simplex algorithm with interactive nodal models. (iPhone/iPad app by Simplex Nodal Limited.)

- Source: https://appshunter.io/ios/app/simplex-nodal/id995736553 (this page in markdown: same URL + `.md`)
- Developer: [Simplex Nodal Limited](https://appshunter.io/developer/995736552)
- Category: Education, Business
- Price: Free
- Age rating: 4+
- Requires: iOS 9.0 · 14 MB
- Languages: American English
- Released: 2015-06-17
- Data updated: 2026-06-04
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/simplex-nodal/id995736553/reviews.md

## What is Simplex Nodal?

In conjunction with the tutorial document, available at www.simplexnodal.com, use the app to learn about electricity markets by graphically building and solving your own electricity market models. The tutorial also describes the simplex algorithm that solves the model and the app lets you see the internal workings of the algorithm. 

Demonstrates nodal electricity markets features such as: locational marginal pricing, line losses, parallel flows, binding constraints, price separation, the spring washer effect, negative prices, risk and reserves, ramp-rates, congestion charges, transmission rentals, multiple electrical islands, HVDC branches, HVDC risk, HVDC risk subtractor, HVDC reserve sharing, and more. 

See www.simplexnodal.com for more screenshots and the tutorial document.

Highlights:
• The tutorial explains nodal electricity markets and the simplex algorithm via worked examples using the app
• Start with small models to learn the basic concepts of the electricity market model the simplex algorithm
• Learn how to explain prices by relaxing constraints to determine shadow prices
• Enable/disable electricity market features to focus on individual effects, e.g., risk and reserve is easier to explain with line losses disabled
• View full details of the simplex modelling including basic and non-basic variables, constraints, shadow prices, and details of the simplex iterations
• Learn how the simplex algorithm works by viewing the step by step simplex operations that solve the electricity market model. View iteration details in the app and/or export the simplex tableaux as a csv file
• The app implements its own simplex algorithm but you can also export the model in GAMS format to solve externally if you have access to the GAMS solver 
• Includes sample models that represent sections of an actual electricity market

iPhone and iPad functionality is the same. Zoom and scroll allow the iPhone to access iPad sized models.

## Key features

- Build and solve electricity market models
- Visualize simplex algorithm workings
- Explore locational marginal pricing
- Understand line losses and binding constraints
- Step-by-step simplex iteration details
- Export simplex tableaux as CSV
- Includes sample market models

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/simplex-nodal/id995736553/reviews.md

### 5/5 — Intuitive interface with great depth and portability

*2015-06-26*

I've used the app to quickly put together ad hoc models of the NZ electricity transmission network. Using the Simplex Nodal example models it's interesting to play with the boundary between the financial market and electrical security to see what really determined prices.

It's useful for my Operations Research uni studies to have a quick reference to remind me of the concepts. I wonder how it would be useful for electrical engineers and sparkys?

The results and model can be emailed out. I've taken them into work and run them through the commercial solvers and the results line up. Reading through the online user guide you can see that it covers all the significant inputs for a working transmission system like optimising energy and reserves and let's you customise even how the electrical losses are calculated.

## Frequently asked questions about Simplex Nodal

### What is Simplex Nodal?

Simplex Nodal is an educational app designed to help users learn about electricity markets and the simplex algorithm. It allows you to build and solve your own market models graphically, visualizing the internal workings of the algorithm.

### How does Simplex Nodal teach about electricity markets?

The app demonstrates key features like locational marginal pricing, line losses, and congestion charges through interactive models. You can enable or disable specific features to focus on individual effects and learn how constraints influence prices.

### Can I see how the simplex algorithm works?

Yes, Simplex Nodal provides detailed step-by-step operations of the simplex algorithm as it solves your market models. You can view iteration details within the app and export the simplex tableaux as a CSV file for further analysis.

### What are the learning resources for Simplex Nodal?

The app is designed to be used in conjunction with a tutorial document available at www.simplexnodal.com. This tutorial explains nodal electricity markets and the simplex algorithm with worked examples that utilize the app.

### Is Simplex Nodal available on multiple devices?

Simplex Nodal is available for iPhone and iPad, offering the same functionality on both. Zoom and scroll features allow iPhone users to access models designed for iPad-sized screens.

### What is the age rating for Simplex Nodal?

Simplex Nodal has an age rating of 4+, making it suitable for a wide range of users interested in learning about these complex topics.

### How often is Simplex Nodal updated?

The app was last updated on May 22, 2020, with version 2.3. While updates may not be frequent, the core functionality for learning electricity markets and the simplex algorithm remains robust.

### Does Simplex Nodal have ads?

No, Simplex Nodal does not contain advertisements. It is a completely ad-free application, allowing for an uninterrupted learning experience.

## Version history (last 5 releases)

### 2.3 — 2020-05-22

Tidied up the displays so they look good on iPhone 11 and iPad (and prepared for macOS... yes, there is now a Mac version).

### 2.2 — 2017-06-05

Fixed the GAMS export, which was working when reserves and losses were included (the sample that was used for testing), but failing for the simpler models when reserves and/or losses were disabled. Also some minor refactoring of the code, all appears to be well, but please report any issues.

### 2.1 — 2016-04-08

Fixes a bug that caused data entry corruption when using a non-English language setting.

### 2.01 — 2015-12-18

2.01 is a minor change to fix blurry screenshots on the load/save displays. 
It is built on top of version 2.0, which added the following:
• Multiple electrical islands, with island based risk and reserve.
• HVDC branch component to connect islands.
• HVDC branch can set risk in receiving island. HVDC risk is modelled separately from AC risk to allow for reserve sharing.
• HVDC risk can be mitigated by adding parallel HVDC branch. The spare capacity on the parallel branch provides a risk subtractor.
• HVDC can share reserve between islands to cover AC risk. This reserve sharing is subject to a capacity constraint, which directionally limits the sum of energy and reserve to the capacity of the HVDC branch.

Also:
• Island colour is selectable.
• Dead component identification. Dead components are excluded from the solve.
• Risk unit and risk setter indication on main display.
• When a bus component is moved, attached branch components are moved or re-sized.
• Option to hide branch names and bus angles.

### 2.0 — 2015-11-15

Multiple electrical islands, with island based risk and reserve.
HVDC branch component to connect islands.
HVDC branch can set risk in receiving island. HVDC risk is modelled separately from AC risk to allow for reserve sharing.
HVDC risk can be mitigated by adding parallel HVDC branch. The spare capacity on the parallel branch provides a risk subtractor.
HVDC can share reserve between islands to cover AC risk. This reserve sharing is subject to a capacity constraint, which directionally limits the sum of energy and reserve to the capacity of the HVDC branch.

Also:
Island colour is selectable.
Dead component identification. Dead components are excluded from the solve.
Risk unit and risk setter indication on main display.
When a bus component is moved, attached branch components are moved or re-sized.
Option to hide branch names and bus angles.

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## More apps by Simplex Nodal Limited

- [GenChange](https://appshunter.io/ios/app/genchange/id1097417274)

All apps by Simplex Nodal Limited: https://appshunter.io/developer/995736552

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-04.*