commonpower.core.Node

class Node(name: str, config: dict = {})

Bases: ControllableModelEntity

Base class providing functionality for busses and components.

Parameters:

• name (str) – Name of the Node object.

• config (dict, optional) – Configuration for defined model elements. Defaults to {}.

Methods

add_data_provider	Adds a data provider to the entity.
add_node	Adds a subordinate node.
add_to_model	This method adds the calling entity to the given (global) pyomo model. To this end, we - declare and add a new pyomo block named by self.id (the entity's global id). - call _get_model_elements() to retrieve the entity's model elements (variables and parameters). - call _augment_model_elements() to add additional model elements (constraints etc.). - check the configuration dict for completeness based on the defined model elements. - add all model elements to the previously declared pyomo block.
clear_data_providers
compute_cost	Computes the cost based on the specified cost_fcn and stores the result in the node's cost parameter.
cost_fcn	Returns the node's cost as pyomo expression at time t.
detach_controller	Remove the current controller from the entity
empty_copy	Creates a fresh copy of the node.
fix_inputs	Set the variables corresponding to inputs to fixed
get_children
get_input_ids	Get identifiers of input elements of a given model instance or self :param model_instance: model to get the input element identifiers for
get_inputs	Extracts model elements of type INPUT from a given model instance or self :param model_instance: model to get the input elements for :type model_instance: ConcreteModel, Optional
get_pyomo_element	Gets a pyomo element referenced by name from the given model.
get_pyomo_element_id	Constructs the global element name from the local name.
get_self_as_pyomo_block	Retrieves the pyomo block of the calling entity from a global model (based on the entity's global id).
get_value	Gets the value of the specified model element.
has_pyomo_element	This is essentially an indicator wrapper around get_pyomo_element() which returns False if no corresponding model element could be found (instead of raising an error).
info	Prints some information about this entity.
input_space	Determines the input space of an entity from the bounds of all model elements with type INPUT within the tree :param normalize: Whether or not to normalize the input space to [-1,1] :type normalize: bool
n_inputs	Total number of model elements with type INPUT within the entire tree of this entity
observation_space	Determines the observation space of an entity based on the observation mask by retrieving the bounds of the model elements listed in the mask
observe	Get observations for one node within the system based on the model items within the observation mask.
register_controller	Register a controller with this node :param controller: controller to be registered :type controller: BaseController
reset	Stores the current global model instance and initializes parameters according to their configuration.
set_id	Generates and sets the node id.
set_value	Sets the value of the specified model element to the specified value.
unmodeled_update	System updates that are not modeled.
update	This reads data providers and executes the dynamics of self and all subordinate nodes.
update_data	Reads data providers for self and all subnodes.
validate_controller	Used to check whether all nodes which require a controller have one assigned.
validate_data_providers	Validates if data providers have compatible configurations.

Attributes

CLASS_INDEX

_add_constraints(model_elements: List[ModelElement]) → List[ModelElement]

This method adds all node constraints

All of this is appended to the given model_elements list and returned.

Parameters:

model_elements (List[ModelElement]) – Model elements list so far

Returns:

List[ModelElement] – Model elements list with appended constraints

classmethod _augment_model_elements(model_elements: List[ModelElement]) → List[ModelElement]

This method adds initial state variables and a cost variable All of this is appended to the given model_elements list and returned.

Parameters:

model_elements (List[ModelElement]) – Model elements list so far.

Returns:

List[ModelElement] – Model elements list with added limit variables and cost variable

_get_additional_constraints() → List[ModelElement]

Returns additional constraints on model variables. This is a utility to keep the _get_model_elements() method clean.

Returns:

List[ModelElement] – List of additional constraint elements.

_get_dynamic_fcn() → List[ModelElement]

Returns constraints on all state variables representing how the states change between timesteps.

Returns:

List[ModelElement] – Generated constraints.

_step_solution()

Steps all variables (except states) forward by one timestep. This is mainly to provide a better warm-start for the solver in the next iteration.

_unmodeled_updates() → None

Unmodeled update actions can be defined here. This could for example be the “true” dynamics of the system, or maniputations of parameters.

_update_data(at_time: datetime)

Reads node data providers.

Parameters:

at_time (datetime) – Timestamp of “now”.

_update_state()

Updates states by moving one timestep “forward”, i.e., state[t] <- state[t+1]. This method can be overwritten by subclasses to implement the “true” dynamics of the system.

add_node(node: Node) → Node

Adds a subordinate node. The added node’s id is set according to its position in the model hierarchy.

Parameters:

node (Node) – Node istance to add.

Returns:

Node – Node instance.

add_to_model(model: ConcreteModel, **kwargs) → None

This method adds the calling entity to the given (global) pyomo model. To this end, we

• declare and add a new pyomo block named by self.id (the entity’s global id).

• call _get_model_elements() to retrieve the entity’s model elements (variables and parameters).

• call _augment_model_elements() to add additional model elements (constraints etc.).

• check the configuration dict for completeness based on the defined model elements.

• add all model elements to the previously declared pyomo block.

We also store a reference to the global model in self.model.

Parameters:

• model (ConcreteModel) – Global pyomo model.

• **kwargs

compute_cost() → None

Computes the cost based on the specified cost_fcn and stores the result in the node’s cost parameter.

cost_fcn(scenario: CostScenario, model: ConcreteModel, t: int = 0) → Expression

Returns the node’s cost as pyomo expression at time t.

\[cost = \sum_{i \in children} cost_i\]

Returns:

Expression – Cost.

empty_copy(with_children: bool = True, with_data_providers: bool = True) → Node

Creates a fresh copy of the node.

Parameters:

• with_children (bool) – Whether to clone the node’s children.

• with_data_providers (bool) – Whether to clone the node’s data providers.

Returns:

Node – Cloned node instance.

reset(instance: ConcreteModel, at_time: datetime) → None

Stores the current global model instance and initializes parameters according to their configuration. It additionally loads the “current” values from data providers.

Parameters:

• instance (ConcreteModel) – Global model instance.

• at_time (datetime) – Timestamp of “now”.

set_id(parent_identity: str = '', number: int = 0) → None

Generates and sets the node id. This is called by the parent entity, i.e., the next higher entity in the object tree.

Parameters:

• parent_identity (str, optional) – Id of the parent entity. Defaults to “”.

• number (int, optional) – Number assigned by the parent entity. Defaults to 0.

unmodeled_update() → None

System updates that are not modeled. This could for example be the “true” dynamics of the system, or maniputations of parameters.

update(at_time: datetime) → None

This reads data providers and executes the dynamics of self and all subordinate nodes. Results are written to current model instance. It also calls _additional_updates().

Parameters:

at_time (datetime) – Timestamp of “now”.

update_data(at_time: datetime)

Reads data providers for self and all subnodes.

Parameters:

at_time (datetime) – Timestamp of “now”.

validate_controller(controller_ids: list, controllers: dict) → Tuple[list, dict]

Used to check whether all nodes which require a controller have one assigned. All unique controllers are added to a list of controllers maintained by the power system.

Parameters:

• controller_ids (list) – unique controller IDs already registered by the system

• controllers (list) – unique controllers already registered by the system

Returns:

list – IDs of controllers within the system dict: dictionary of {controller_id: controller} within the system

validate_data_providers(horizon: timedelta, tau: timedelta) → None

Validates if data providers have compatible configurations.

Parameters:

• horizon (timedelta) – Forecast horizon.

• tau (timedelta) – Sample time.