modelSecondOrderPlant

Information

1. Purpose of model

This simple power plant model takes the target power output as an input (u) and considers a given ramp rate (P_el_grad in % P_el_n per minute) to deliver a power output (epp.P).

The model can be tested with the following examples:

• TransiEnt.Producer.Electrical.Conventional.Check.TestSecondOrderContiuousPlant_PlantStart and
• TransiEnt.Producer.Electrical.Conventional.Check.TestSecondOrderContiuousPlant_VDIVDE3507

The model calculates the plant's fuel consumption based on the plant's efficiency, which in turn is dependent on the plant's operation point.

An example of the usage of this component be found in TransiEnt.Producer.Electrical.Conventional.Check.TestSecondOrderContiuousPlant

The model can be used once the following parameters have been defined:

Physical restrictions:

P_n: nominal power of the plant. It is used to calculate the plant's investment costs.

eta_total: nominal efficiency of the plant at full load. It is used together with the part load charline to calculate the plant's efficiency at different loads

PartLoadCharline: It is used together with the eta_load parametercalculate the plant's efficiency at different loads. For further description refer to the documentation of TransiEnt.Producer.Electrical.Base.RelativePartloadEfficiency

P_el_grad:

P_el_max and P_el_min are currently not in use. These restrictions should be taken into consideration by the power dispatch algorithm.

Statistics:

Type of resource: for energy allocation statistics

Type of primary energy carrier: for CO2 emissions calculation

Producer costs: for economic calcualations

2. Level of detail, physical effects considered, and physical insight

Part load behaviour

The part-load behaviour of the plant is calculated by multiyplying the nominal plant efficiency with the relative part load characteristic line of the selected type of plant.

Further details regarding the part load efficiencies can be found in the documentation of the package TransiEnt.Producer.Electrical.Base.RelativePartloadEfficiency

Typical resulting part load efficiencies are shown bellow:

Time-dependent behaviour

This model makes use of simple proportionality rules to roughly depict the dynamic behaviour of a power plant's output to a certain extent. The model however is far from being a physically accurate model of the plant's dynamics. The model considers

The definition of the time constant () of a first order linear time-invariant system is used to set the reference values of the proportionality, i.e. the time constant as the time after which the response of a system to a step function reaches the 63.2% of the set value.

Using proportionality rules, the time constant of the model's first order block is definied as a function of the power plant's nominal ramp rate as follows:

This leads to the equation:

3. Limits of validity

- This plant model is "always on" meaning that it reacts to power setpoint without delay even if current output is zero

- Control power provision is not implemented

4. Interfaces

u: RealInput

epp: type of electrical power port can be chosen

5. Nomenclature

no elements

6. Governing Equations

no equations

7. Remarks for Usage

Recomended nominal efficiencies (based on Strauß, 2009):

Steam power plant (hard coal) --> 0.40 - 0.45

Combined Cycle --> 0.60

GasTurbines --> 0.32

Recommended ramp rates in % P_el_n per minute (based on Brauner et. al., 2012):

Steam power plant (hard coal) --> 4 to 6

Steam power plant (lignite) --> 2.5 to 4

Combined Cycle power plant --> 4 to 8

Gas turbine --> 12 to 15

8. Validation

Instead of a validation, the plausibility of the results will be model results has been roughly proofed.

The results obtained with this model in the test-model TransiEnt.Producer.Electrical.Conventional.Check.TestSecondOrderContiuousPlant_PlantStart are shown bellow together with rough reference values from [2] are displayed bellow.

9. References

[1] Strauß, Karl: Kraftwerkstechnik zur Nutzung fossiler, nuklearer und regenerativer Energiequellen. 6. ed. Heidelberg : Springer-Verlag Berlin Heidelberg, 2009 — ISBN 9783642014307

[2] Brauner, Günther ; Glaunsinger, Wolfgang ; Bofinger, Stefan ; John, Markus ; Magin, Wendelin ; Pyc, Ireneusz ; Schüler, Steffen ; Schulz, Stephan ; Schwing, Ulrich ; et al.: Erneuerbare Energie braucht flexible Kraftwerke - Szenarien bis 2020 : Verband der Elektrotechnik Elektronik Informationstechnik e.V., 2012

10. Version History

Model generalized for different electrical power ports by Jan-Peter Heckel (jan.heckel@tuhh.de) in July 2018

Parameters

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Components