|
|
The following attempts to explain the different entities that constitute the modelled energy network, namely grids, nodes, and units (Figure 1). The descriptions below attempt to remain on a rather high level, without overly detailed explanations about all the parameters etc. in the code that are required for actually realizing the described properties.
|
|
|
|
|
|
![JuhanVerkko](/uploads/f4090d494d01fbd080efd1b3a099b51b/JuhanVerkko.png)
|
|
|
|
|
|
In the above picture, ovals represent nodes, rectangles represent units, and color is used to imply different grids. Arrows are used to indicate either transfer of diffusion of energy between the different nodes.
|
|
|
|
|
|
# Grids
|
|
|
|
|
|
Grids are essentially groups of nodes with a common form of energy. The primary purpose of the grid dimension is to organize the nodes into grids so that the results are easier to decipher. Furthermore, the diffusion and transfer of energy between nodes located in different grids is not permitted directly, even though there could possibly be some niche applications. Instead, controlled transfer of energy between grids is referred to as “conversion” and handled by units, which will be explained later. However, it would make no difference for the functioning of said conversion unit even if all the nodes were included in the same grid.
|
|
|
|
|
|
# Nodes
|
|
|
|
|
|
Nodes are what constitute the “network” part of Backbone, and they are arguably the most important part of the model framework. The nature of the nodes depends heavily on their properties, which makes them a little difficult to explain in any concise way. However, the one common thing with all the nodes is that energy balance is enforced at each defined node.
|
|
|
Nodes have properties in addition to their (unique) name. The most important properties of nodes are the following:
|
|
|
|
|
|
+ State: E.g. the energy content or the temperature of the node. Nodes are not required to have a state, which means that the node cannot store energy. The quality of the state is defined by various parameters, and one has to be careful to assign the values of said parameters correctly.
|
|
|
|
|
|
+ This is one of the reasons why grids prevent direct energy transfer between each other, as direct transfer of e.g. temperature into electricity would not make sense. This is mostly just a safeguard, because linear conversion could be considered using transfer efficiency parameters between grids.
|
|
|
|
|
|
+ Various boundary conditions can be imposed on the state of a node, ranging from the simple absolute upper and lower bounds to “softer” bounds that can be exceeded at the cost of a separately defined penalty. These bounds can be set to be constant, or follow some pre-determined time series. It is also possible to constrain a state of a node relative to the state of some other node.
|
|
|
|
|
|
+ Diffusion: Nodes can be connected to other nodes in the same grid via diffusion coefficients, causing energy to uncontrollably leak from one node to another depending on the states of said nodes. Diffusion coefficients can technically be defined even for nodes without states, even though they will have no effect on anything in that case (non-existent states contain zero energy).
|
|
|
|
|
|
+ Diffusion between grids is not permitted at the moment as a safeguard.
|
|
|
|
|
|
+ Diffusion can be defined to be asymmetric, resulting in a one-directional uncontrolled flow of energy from one node to another.
|
|
|
|
|
|
+ Self-discharge of energy from the nodes outside the model scope is also possible using a separate parameter.
|
|
|
|
|
|
+ Transfer: Nodes can also be connected to other nodes in the same grid via controlled transfer, which can be defined as both one- or two-directional. Naturally, boundaries on the transfer capabilities of nodes can be imposed using various parameters.
|
|
|
|
|
|
+ Reserve requirements: Just as the energy balance is enforced on the nodal level, so are the possible requirements for reserves.
|
|
|
|
|
|
+ Spill capability: Nodes can be permitted to spill energy, essentially transferring it outside the model boundaries.
|
|
|
|
|
|
+ Contain units: Even though units are a separate entity altogether, each unit must be connected to at least one node.
|
|
|
|
|
|
# Units
|
|
|
|
|
|
While nodes handle the flow of energy in the different grids, they lack the capability to create, consume, and convert energy between grids. Similar to nodes, there is a lot of different ways that units can be made to function, depending on the parameters given in the input data. The most important properties of units are briefly explained below.
|
|
|
|
|
|
+ Generation and consumption of energy: The quintessential property of units is the capability to generate energy to a node, or consume it.
|
|
|
|
|
|
+ While units can be defined to generate limitless free energy out of thin air, more often the generated energy is defined to increase the consumption of defined fuels (which usually have a cost attributed to them), or have limited generation capabilities based on data (solar, wind, hydro).
|
|
|
|
|
|
+ Consumption of energy is treated as “negative generation” when it comes to units, and unless some form of energy conversion is defined for the unit in question, the consumed energy is transferred out of the model boundaries.
|
|
|
|
|
|
+ While nodes could be used to emulate some of the functionality of the units, units provide parameters capable of defining the way energy generation and consumption work in much more detail.
|
|
|
|
|
|
+ Conversion of energy between grids: While energy can diffuse and be transferred between nodes within each grid, units are currently the only way of transferring (referred to as conversion for units) energy between nodes in different grids.
|
|
|
|
|
|
+ This functionality essentially means that a unit can be connected to multiple nodes, and the energy generation and consumption variables in each node are linked to each other according to desired conversion rules and constraints. |
|
|
\ No newline at end of file |