[TASK] Blackbox dispatch optimization

[dhill2522]

---

Issue Description

There are some cases where a user may want or need to use arbitrary, non-linear, non-differentiable transfer functions in a dispatch optimization problem. While this is clearly less efficient than current methods, this allows optimization for systems where the transfer function is determined by lookup tables, external simulations or simply non-linear functions not currently supported using the existing Pyomo dispatcher.

The proposal is to allow for such transfer functions by implementing a dispatcher that makes use of transfer functions defined as methods in an external Python script. These methods could then be referred to in the heron input file using the Function node within the transfer node for Heron components.

---

For Change Control Board: Issue Review

This review should occur before any development is performed as a response to this issue.

• 1. Is it tagged with a type: defect or task?
• 2. Is it tagged with a priority: critical, normal or minor?
• 3. If it will impact requirements or requirements tests, is it tagged with requirements?
• 4. If it is a defect, can it cause wrong results for users? If so an email needs to be sent to the users.
• 5. Is a rationale provided? (Such as explaining why the improvement is needed or why current code is wrong.)

---

For Change Control Board: Issue Closure

This review should occur when the issue is imminently going to be closed.

• 1. If the issue is a defect, is the defect fixed?
• 2. If the issue is a defect, is the defect tested for in the regression test system? (If not explain why not.)
• 3. If the issue can impact users, has an email to the users group been written (the email should specify if the defect impacts stable or master)?
• 4. If the issue is a defect, does it impact the latest release branch? If yes, is there any issue tagged with release (create if needed)?
• 5. If the issue is being closed without a pull request, has an explanation of why it is being closed been provided?