Types of energy system components

This chapter provides details on the parameters of energy system components, which can be used in the project input file. For a detailed description of the mathematical models, see the chapter on the component models.

The description of each component type includes a block with a number of attributes that describe the type and how it connects to other components by its input and output interfaces. An example of such a block:

Type name	BoundedSink
File	energy_systems/general/bounded_sink.jl
Available models	default
System function	bounded_sink
Medium	medium/None
Input media	None/auto
Output media
Tracked values	IN, Max_Energy, Losses

The available models listed are subtypes to the implementation of a component, which each work slightly differently and might use different parameters. An example is the difference between a condensing gas boiler and a traditional one. Note: At the moment there is no argument for the model, as each component currently only has one implemented model. In the future this will be extended to include a default model (when no argument is provided) and additional optional models.

Of particular note are the descriptions of the medium (if it applies) of the component type and its input and output interfaces. The Medium is used for components that could handle any type of medium and need to be configured to work with a specific medium. The attributes Input media and Output media describes which input and output interfaces the type provides and how the media of those can be configured. The syntax name:value lists the name of the parameter in the input data that defines the medium first, followed by a forward slash and the default value of the medium second, if any. A value of None implies that no default is set and therefore it must be given in the input data. A value of auto implies that the value is determined with no required input, usually from the Medium.

The Tracked values attribute lists which values of the component can be tracked with the output specification in the input file (see this section for details). Note that a value of IN or OUT refers to all input or output interfaces of the component. Which these are can be infered from the input and output media attributes and the chosen medium names if they differ from the default values.

The description further lists which arguments the implementation takes. Let's take a look at an example:

Name	Type	R/D	Example	Description
max_power_profile_file_path	String	Y/N	profiles/district/max_power.prf	Path to the max power profile.
efficiency	Float	Y/Y	0.8	Ratio of output over input energies.
constant_temperature	Temperature	N/N	65.0	If given, sets the temperature of the heat output to a constant value.

The name of the entries should match the keys in the input file, which is carried verbatim as entries to the dictionary argument of the component's constructor. The column R/D lists if the argument is required (R) and if it has a default value (D). If the argument has a default value the example value given in the next column also lists what that default value is. Otherwise the example column shows what a value might look like.

The type refers to the type it is expected to have after being parsed by the JSON library. The type Temperature is an internal structure and simply refers to either Float or Nothing, the null-type in Julia. In general, a temperature of Nothing implies that any temperature is accepted and only the amount of energy is revelant. More restrictive number types are automatically cast to their superset, but not the other way around, e.g: $UInt \rightarrow Int \rightarrow Float \rightarrow Temperature$. Dictionaries given in the {"key":value} notation in JSON are parsed as Dict{String,Any}.

Storage un-/loading

All components can be set to be dis-/allowed to un-/load storages to which they output or from which they draw energy. This only makes sense if an intermediary bus exists as direct connections to/from storages must always be allowed to transfer energy. The flags to control this behaviour are set in the strategy part of the parameter specification (compare component specification). Here are exemplary parameters for a bounded supply:

{
    "uac": "TST_SRC_01",
    "type": "BoundedSupply",
    "medium": "m_h_w_lt1",
    ...
    "strategy": {
        "name": "default",
        "load_storages m_h_w_lt1": false
    }
}

This would result in the energy the source supplies not being used to fill storages. The medium name m_h_w_lt1 is, in this case, derived from the parameter medium. The load_storages medium parameter must match the name of the medium of the input/output, however that is set or derived. For controlling, if components can draw energy from storages, the corresponding unload_storages medium parameter can be used.

Boundary and connection components

General bounded sink

Type name	BoundedSink
File	energy_systems/general/bounded_sink.jl
Available models	default
System function	bounded_sink
Medium	medium/None
Input media	None/auto
Output media
Tracked values	IN, Max_Energy, Temperature

Generalised implementation of a bounded sink.

Can be given a profile for the maximum power it can take in, which is scaled by the given scale factor. If the medium supports it, a temperature can be given, either as profile from a .prf file or from the ambient temperature of the project-wide weather file or a constant temperature can be set.

Name	Type	R/D	Example	Description
max_power_profile_file_path	String	N/N	profiles/district/max_power.prf	Path to the max power profile.
constant_power	Temperature	N/N	4000.0	If given, sets the max power of the input to a constant value.
scale	Float	N/Y	1.0	Factor by which the max power values are multiplied. Only applies to profiles.
temperature_profile_file_path	String	N/N	profiles/district/temperature.prf	Path to the profile for the input temperature.
constant_temperature	Temperature	N/N	65.0	If given, sets the temperature of the input to a constant value.
temperature_from_global_file	String	N/N	temp_ambient_air	If given, sets the temperature of the input to the ambient air temperature of the global weather file.

Note that either temperature_profile_file_path, static_temperature or temperature_from_global_file (or none of them) should be given!

General bounded supply

Type name	BoundedSupply
File	energy_systems/general/bounded_supply.jl
Available models	default
System function	bounded_source
Medium	medium/None
Input media
Output media	None/auto
Tracked values	OUT, Max_Energy, Temperature

Generalised implementation of a bounded source.

Can be given a profile for the maximum power it can provide, which is scaled by the given scale factor. If the medium supports it, a temperature can be given, either as profile from a .prf file or from the ambient temperature of the project-wide weather file or a constant temperature can be set.

Name	Type	R/D	Example	Description
max_power_profile_file_path	String	N/N	profiles/district/max_power.prf	Path to the max power profile.
constant_power	Temperature	N/N	4000.0	If given, sets the max power of the output to a constant value.
scale	Float	N/Y	1.0	Factor by which the max power values are multiplied. Only applies to profiles.
temperature_profile_file_path	String	N/N	profiles/district/temperature.prf	Path to the profile for the output temperature.
constant_temperature	Temperature	N/N	65.0	If given, sets the temperature of the output to a constant value.
temperature_from_global_file	String	N/N	temp_ambient_air	If given, sets the temperature of the input to the ambient air temperature of the global weather file.

Note that either temperature_profile_file_path, static_temperature or temperature_from_global_file (or none of them) should be given!

Bus

Type name	Bus
File	energy_systems/connections/bus.jl
Available models	default
System function	bus
Medium	medium/None
Input media	None/auto
Output media	None/auto
Tracked values	Balance, Transfer->UAC

The only implementation of special component Bus, used to connect multiple components with a shared medium.

Note that the tracked value Transfer->UAC refers to an output value that corresponds to how much energy the bus has transfered to the bus with the given UAC.

Name	Type	R/D	Example	Description
connections	Dict{String,Any}	N/N		Connection config for the bus. See chapter on the input file format for details.

General fixed sink

Type name	FixedSink
File	energy_systems/general/fixed_sink.jl
Available models	default
System function	fixed_sink
Medium	medium/None
Input media	None/auto
Output media
Tracked values	IN, Demand, Temperature

Generalised implementation of a fixed sink.

Can be given a profile for the energy it requests, which is scaled by the given scale factor. Alternatively a static load can be given. If the medium supports it, a temperature can be given, either as profile from a .prf file or from the ambient temperature of the project-wide weather file or a constant temperature can be set.

Name	Type	R/D	Example	Description
energy_profile_file_path	String	N/N	profiles/district/demand.prf	Path to the input energy profile.
constant_demand	Float	N/N	4000.0	[power, not work!] If given, ignores the energy profile and sets the input demand to this constant power.
scale	Float	N/Y	1.0	Factor by which the energy profile values are multiplied. Only applies to profiles.
temperature_profile_file_path	String	N/N	profiles/district/temperature.prf	Path to the profile for the input temperature.
constant_temperature	Temperature	N/N	65.0	If given, sets the temperature of the input to a constant value.
temperature_from_global_file	String	N/N	temp_ambient_air	If given, sets the temperature of the input to the ambient air temperature of the global weather file.

Note that either temperature_profile_file_path, static_temperature or temperature_from_global_file (or none of them) should be given!

General demand

Type name	Demand
File	energy_systems/general/fixed_sink.jl
Alias to FixedSink.

General fixed supply

Type name	FixedSupply
File	energy_systems/general/fixed_supply.jl
Available models	default
System function	fixed_source
Medium	medium/None
Input media
Output media	None/auto
Tracked values	OUT, Supply, Temperature

Generalised implementation of a fixed source.

Can be given a profile for the energy it can provide, which is scaled by the given scale factor. If the medium supports it, a temperature can be given, either as profile from a .prf file or from the ambient temperature of the project-wide weather file or a constant temperature can be set.

Name	Type	R/D	Example	Description
energy_profile_file_path	String	N/N	profiles/district/energy_source.prf	Path to the output energy profile.
constant_supply	Float	N/N	4000.0	[power, not work!] If given, ignores the energy profile and sets the output supply to this constant power.
scale	Float	N/Y	1.0	Factor by which the energy profile values are multiplied. Only applies to profiles.
temperature_profile_file_path	String	N/N	profiles/district/temperature.prf	Path to the profile for the output temperature.
constant_temperature	Temperature	N/N	65.0	If given, sets the temperature of the output to a constant value.
temperature_from_global_file	String	N/N	temp_ambient_air	If given, sets the temperature of the input to the ambient air temperature of the global weather file.

Note that either temperature_profile_file_path, static_temperature or temperature_from_global_file (or none of them) should be given!

Grid connection

Type name	GridConnection
File	energy_systems/connections/grid_connection.jl
Available models	default
System function	bounded_source, bounded_sink
Medium	medium/None
Input media	None/auto
Output media	None/auto
Tracked values	IN, OUT, Input_sum, Output_sum

Used as a source or sink with no limit, which receives or gives off energy from/to outside the system boundary.

If parameter is_source is true, acts as a bounded_source with only one output connection. Otherwise a bounded_sink with only one input connection. In both cases the amount of energy supplied/taken in is tracked as a cumulutative value.

Name	Type	R/D	Example	Description
is_source	Boolean	Y/Y	True	If true, the grid connection acts as a source.

Other sources and sinks

Photovoltaic plant

Type name	PVPlant
File	energy_systems/electric_producers/pv_plant.jl
Available models	default: simplified
System function	fixed_source
Medium
Input media
Output media	m_el_out/m_e_ac_230v
Tracked values	OUT, Supply

A photovoltaic (PV) power plant producing electricity.

The energy it produces in each time step must be given as a profile, but can be scaled by a fixed value.

Name	Type	R/D	Example	Description
energy_profile_file_path	String	Y/N	profiles/district/pv_output.prf	Path to the output energy profile.
scale	Float	Y/N	4000.0	Factor by which the profile values are multiplied.

Transformers

Combined Heat and Power plant

Type name	CHPP
File	energy_systems/electric_producers/chpp.jl
Available models	default: simplified
System function	transformer
Medium
Input media	m_gas_in/m_c_g_natgas
Output media	m_heat_out/m_h_w_ht1, m_el_out/m_e_ac_230v
Tracked values	IN, OUT, Losses

A Combined Heat and Power Plant (CHPP) that transforms combustible gas into heat and electricity.

Name	Type	R/D	Example	Description
power_gas	Float	Y/N	4000.0	The maximum design power input (chemical input power).
electricity_fraction	Float	Y/Y	0.4	Fraction of the input chemical energy that is output as electricity.
min_power_fraction	Float	Y/Y	0.2	The minimum fraction of the design power_gas that is required for the plant to run.
min_run_time	UInt	Y/Y	1800	Minimum run time of the plant in seconds. Will be ignored if other constraints apply.
output_temperature	Temperature	N/N	90.0	The temperature of the heat output.

Electrolyser

Type name	Electrolyser
File	energy_systems/others/electrolyser.jl
Available models	default: simplified
System function	transformer
Medium
Input media	m_el_in/m_e_ac_230v
Output media	m_heat_out/m_h_w_lt1, m_h2_out/m_c_g_h2, m_o2_out/m_c_g_o2
Tracked values	IN, OUT, Losses, Losses_heat, Losses_hydrogen

Implementation of an electrolyser splitting water into hydrogen and oxygen while providing the waste heat as output.

Name	Type	R/D	Example	Description
power_el	Float	Y/N	4000.0	The maximum electrical design power input.
min_power_fraction	Float	Y/Y	0.2	The minimum fraction of the design power_el that is required for the plant to run.
heat_fraction	Float	Y/Y	0.4	Fraction of the input electric energy that is output as heat.
min_run_time	UInt	Y/Y	1800	Minimum run time of the plant in seconds. Will be ignored if other constraints apply.
output_temperature	Temperature	N/Y	55.0	The temperature of the heat output.

Fuel boiler

Type name	FuelBoiler
File	energy_systems/heat_producers/fuel_boiler.jl
Available models	default: simplified
System function	transformer
Medium
Input media	m_fuel_in
Output media	m_heat_out/m_h_w_ht1
Tracked values	IN, OUT, Losses

A boiler that transforms chemical fuel into heat.

This needs to be parameterized with the medium of the fuel intake as the implementation is agnostic towards the kind of fuel under the assumption that the fuel does not influence the behaviour or require/produce by-products such as pure oxygen or ash (more to the point, the by-products do not need to be modelled for an energy simulation.)

The current implementation includes functionality to model a PLR-dependant thermal efficiency $\eta(PLR)$, however the efficiency curve is not customizable without code changes until a system for functions-as-parameters is in place.

Name	Type	R/D	Example	Description
m_fuel_in	String	Y/N	m_c_g_natgas	The medium of the fuel intake.
power_th	Float	Y/N	4000.0	The maximum thermal design power output.
min_power_fraction	Float	Y/Y	0.2	The minimum fraction of the design power_th that is required for the plant to run.
min_run_time	UInt	Y/Y	1800	Minimum run time of the plant in seconds. Will be ignored if other constraints apply.
output_temperature	Temperature	N/N	90.0	The temperature of the heat output.
max_thermal_efficiency	Float	N/Y	1.0	The maximum thermal efficiency if no $\eta(PLR)$ is used.
is_plr_dependant	Boolean	N/Y	False	Toggle if $\eta(PLR)$ is used or not.

Heat pump

Type name	HeatPump
File	energy_systems/heat_producers/heat_pump.jl
Available models	default: carnot
System function	transformer
Medium
Input media	m_el_in/m_e_ac_230v, m_heat_in/m_h_w_lt1
Output media	m_heat_out/m_h_w_ht1
Tracked values	IN, OUT, COP, Losses

Elevates supplied low temperature heat to a higher temperature with input electricity.

Name	Type	R/D	Example	Description
power_th	Float	Y/N	4000.0	The thermal design power at the heating output.
min_power_fraction	Float	Y/Y	0.2	The minimum fraction of the design power_th that is required for the plant to run.
min_run_time	UInt	Y/Y	1800	Minimum run time of the plant in seconds. Will be ignored if other constraints apply.
constant_cop	Float	N/N	3.0	If given, ignores the dynamic COP calculation and uses a constant value.
input_temperature	Temperature	N/N	20.0	If given, ignores the supplied temperature and uses a constant one.
output_temperature	Temperature	N/N	65.0	If given, ignores the requested temperature and uses a constant one.

Storage

General storage

Type name	Storage
File	energy_systems/general/storage.jl
Available models	default: simplified
System function	storage
Medium	medium/None
Input media	None/auto
Output media	None/auto
Tracked values	IN, OUT, Load, Load%, Capacity, Losses

A generic implementation for energy storage technologies.

Name	Type	R/D	Example	Description
capacity	Float	Y/N	12000.0	The overall capacity of the storage.
load	Float	Y/N	6000.0	The initial load state of the storage.

Battery

Type name	Battery
File	energy_systems/storage/battery.jl
Available models	default: simplified
System function	storage
Medium	medium/m_e_ac_230v
Input media	None/auto
Output media	None/auto
Tracked values	IN, OUT, Load, Load%, Capacity, Losses

A storage for electricity.

Name	Type	R/D	Example	Description
capacity	Float	Y/N	12000.0	The overall capacity of the battery.
load	Float	Y/N	6000.0	The initial load state of the battery.

Buffer Tank

Type name	BufferTank
File	energy_systems/storage/buffer_tank.jl
Available models	default: simplified
System function	storage
Medium	medium/m_h_w_ht1
Input media	None/auto
Output media	None/auto
Tracked values	IN, OUT, Load, Load%, Capacity, Losses

A short-term storage for heat of thermal carrier fluids, typically water.

Model simplified:

If the adaptive temperature calculation is activated, the temperatures for the input/output of the BT depends on the load state. If it is sufficiently full (depends on the switch_point), the BT can output at the high_temperature and takes in at the high_temperature. If the load falls below that, the output temperature drops and reaches the low_temperature as the load approaches zero.

If the adaptive temperature calculation is deactivated, always assumes the high_temperature for both input and output.

Name	Type	R/D	Example	Description
capacity	Float	Y/N	12000.0	The overall capacity of the BT.
load	Float	Y/N	6000.0	The initial load state of the BT.
use_adaptive_temperature	Float	Y/Y	False	If true, enables the adaptive output temperature calculation.
switch_point	Float	Y/Y	0.15	Partial load at which the adaptive output temperature calculation switches.
high_temperature	Temperature	Y/Y	75.0	The high end of the adaptive in-/output temperature.
low_temperature	Temperature	Y/Y	20.0	The low end of the adaptive in-/output temperature.

Seasonal thermal storage

Type name	SeasonalThermalStorage
File	energy_systems/storage/seasonal_thermal_storage.jl
Available models	default: simplified
System function	storage
Medium
Input media	m_heat_in/m_h_w_ht1
Output media	m_heat_out/m_h_w_lt1
Tracked values	IN, OUT, Load, Load%, Capacity, Losses

A long-term storage for heat stored in a stratified artificial aquifer.

Model simplified:

If the adaptive temperature calculation is activated, the temperatures for the input/output of the STES depends on the load state. If it is sufficiently full (depends on the switch_point), the STES can output at the high_temperature and takes in at the high_temperature. If the load falls below that, the output temperature drops and reaches the low_temperature as the load approaches zero.

If the adaptive temperature calculation is deactivated, always assumes the high_temperature for both input and output.

Name	Type	R/D	Example	Description
capacity	Float	Y/N	12000.0	The overall capacity of the STES.
load	Float	Y/N	6000.0	The initial load state of the STES.
use_adaptive_temperature	Float	Y/Y	False	If true, enables the adaptive output temperature calculation.
switch_point	Float	Y/Y	0.25	Partial load at which the adaptive output temperature calculation switches.
high_temperature	Temperature	Y/Y	90.0	The high end of the adaptive in-/output temperature.
low_temperature	Temperature	Y/Y	15.0	The low end of the adaptive in-/output temperature.