modelFlywheelStorage_L2
Extends from TransiEnt.Storage.Electrical.Base.PartialElectricStorage (Most abstract model of an electric storage unit), TransiEnt.Basics.Icons.Flywheel.
Information
1. Purpose of model
Model of an electric storage device based on flywheel technology.
2. Level of detail, physical effects considered, and physical insight
Physical representation of losses due to bearing and aerodynamic friction.
3. Limits of validity
Wear-out of component is not taken into account. This model has ideal reaction speeds.
4. Interfaces
There is only one electric port. Power input/output is regulated by grid frequency.
5. Nomenclature
(no elements)
6. Governing Equations
E=1/2*J*w^2
P_max = w*M_max
P=(f-f_n)*k
w_min<w<w_max
Losses:
Bearing losses proportional to w:
P_loss_bearing=a*w
Aerodynamic losses proportional to w^3:
P_loss_aerodynamic = b *w^3
Losses due to support system constant:
P_loss_support=const
7. Remarks for Usage
The flywheel will need the power to sustain its rotational speed when empty. Otherwise the simulation will fail.
8. Validation
Values for eta_max and self discharge rate compared to specification sheets. Thus, the loss factors a and b can be assumed to be in the right order of magnitude for the referenced system.
9. References
[1]Beacon power, LLS, URL: http://beaconpower.com/
10. Version History
Model created by Arne Koeppen (arne.koeppen@tuhh.de), Jul 2013
Edited by Lisa Andresen (andresen@tuhh.de) Aug 2013
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Storage.Electrical.Specifications.DetailedFlywheel.GenericFlywheelRecord | params | Model to use | |
| Modelica.Units.NonSI.Energy_kWh | E_start | E_max | Initial Energy |
| SI.Energy | K | 2e6 | Power response per Hz deviation |
| Modelica.Units.NonSI.AngularVelocity_rpm | n_max | params.n_max | Maximum revolution speed in rpm |
| Modelica.Units.NonSI.AngularVelocity_rpm | n_min | params.n_min | Minimum revolution speed in rpm |
| Modelica.Units.NonSI.Energy_kWh | E_max | params.E_max | Maximum storable energy in kWh |
| SI.Power | P_el_max | params.P_el_max | Absolute maximum power |
| SI.Power | P_loss_support | params.P_loss_support | Power needed to uphold operation |
| Real | eta | params.eta_max | Maximum efficiency of a cycle |
| SI.Time | tau | params.tau | Time constant for self discharge |
| Real | eta_conv | params.eta_conv | Efficiency of conversion |
| SI.Energy | E_stor_max | Modelica.Units.Conversions.from_kWh(E_max) | |
| SI.AngularFrequency | omega_max | Modelica.Units.Conversions.from_rpm(n_max) | |
| SI.AngularFrequency | omega_min | Modelica.Units.Conversions.from_rpm(n_min) | |
| Real | lossFactor_bear | params.lossFactor_bear | |
| Real | lossFactor_aero | params.lossFactor_aero | |
| SI.Energy | E_rot_max | E_stor_max + E_rot_min | |
| SI.Energy | E_rot_min | 1/2*omega_min^2*J | Rotational kinetic energy at omega_min |
| SI.MomentOfInertia | J | 2*(E_rot_max)/omega_max^2 | Moment of inertia of flywheel |
| SI.MomentOfForce | M_max | P_el_max/omega_max | Maximum allowed momentum on flywheel |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Basics.Interfaces.Electrical.ActivePowerPort | epp (from PartialElectricStorage) | ||
| Modelica.Blocks.Interfaces.RealOutput | SOC | E_stor/E_stor_max | State of Charge |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.SimCenter | simCenter | ||
| Modelica.Units.SI.Energy | E_rot | Rotational energy | |
| SI.Frequency | f | actual grid frequency | |
| SI.ActivePower | P | Power on epp | |
| SI.Energy | E_stor | Available energy in Storage | |
| SI.AngularFrequency | omega | Angular velocity of flywheel | |
| SI.Power | P_omega_max | Maximum power output at current omega | |
| SI.Power | P_loss_conversion | Energy loss due to standbylosses | |
| SI.Power | P_loss_bear | Losses due to the bearing | |
| SI.Power | P_loss_aero | Aerodynamic losses | |
| SI.Power | P_loss | Summed losses | |
| SI.Power | P_demand | ||
| SI.Energy | E_pos | Positive (delivered) energy | |
| SI.Energy | E_neg | Negative (stored) energy | |
| SI.Energy | eta_is | E_pos/max(E_stor_max, E_neg) | Actual efficiency |